Electrical control of magnetic order remains one of the fundamental pursuits in condensed matter physics and spintronics, offering transformative potential for energy-efficient, high-density information technologies. While current-induced switching via spin-transfer and spin-orbit torques is well established in ferromagnets, electrically driving a transition between distinct magnetic phases, specifically from a ferromagnetic to an antiferromagnetic state, remains largely unexplored experimentally. Here, we demonstrate a reversible, electrically-driven inverse metamagnetic transition in an epitaxial thin film of the correlated manganite Sm1-xSrxMnO₃. Above a critical current threshold, the system abruptly switches from a low-resistance ferromagnetic state to a high-resistance antiferromagnetic-like phase. We exploit this phenomenon in nanoscale (250 × 250 nm²) spin-filter tunnel junctions based on LaNiO₃/Sm₀.₇₅Sr₀.₂₅MnO₃/ SrTiO₃/La₀.₇Sr₀.₃MnO₃ heterostructures, realizing robust, bistable resistance switching with unconventional magnetoresistance exceeding 200 %, tunable by current, temperature, and magnetic field. These findings open a phase-transition-based route for electrically driven spintronic devices beyond conventional torque-based strategies.

Abstract Electrical control of magnetic order remains one of the fundamental pursuits in condensed matter physics and spintronics, offering transformative potential for energy-efficient, high-density information technologies. While current-induced switching via spin-transfer and spin-orbit torques is well established in ferromagnets, electrically driving a transition between distinct magnetic phases, specifically from a ferromagnetic to an antiferromagnetic state, remains largely unexplored experimentally. Here, we demonstrate a reversible, electrically-driven inverse metamagnetic transition in an epitaxial thin film of the correlated manganite Sm 1-x Sr x MnO₃. Above a critical current threshold, the system abruptly switches from a low-resistance ferromagnetic state to a high-resistance antiferromagnetic-like phase. We exploit this phenomenon in nanoscale (250 × 250 nm²) spin-filter tunnel junctions based on LaNiO₃/Sm₀.₇₅Sr₀.₂₅MnO₃/ SrTiO₃/La₀.₇Sr₀.₃MnO₃ heterostructures, realizing robust, bistable resistance switching with unconventional magnetoresistance exceeding 200 %, tunable by current, temperature, and magnetic field. These findings open a phase-transition-based route for electrically driven spintronic devices beyond conventional torque-based strategies.

The ability to use an applied voltage to effectively manipulate perpendicular magnetic anisotropy is critical for high density, robust magnetic random access memory devices. Using first principle simulations, we examine voltage control of perpendicular magnetic anisotropy at the interface between Fe and several different spinel oxides ( MgAl2O4, MgGa2O 4, and ZnAl (2) O (4)). These spinel oxides have an excellent lattice match with Fe and there is good alignment of spinel O atoms with Fe atoms at the interface. We find that all of these Fe |spinel oxide interfaces have high perpendicular magnetic anisotropy ranging from 1.87 to 1.89 mJ / m 2. The two Fe layers closest to the oxide interface provide significant contributions to the magnetic anisotropy. Calculations for Cu |Fe |spinel slabs under applied fields indicate VCMA coefficients in the range of (25-30 fJ V m) which are comparable to that found for Fe |MgO. Given the excellent lattice match with (001) bcc Fe for all of these spinel oxides and the demonstrated high TMR for the case of Fe | MgAl2O 4, our results indicate that members of this spinel oxide family are promising candidates for tunneling barriers in future voltage controlled MRAM devices.

Today's transistors dictate the voltage and charge scales for both logic and memory. While AI systems are recognized to be limited by memory energy, the dominant share of the energy is expended in the intrachip interconnects whose voltage and charge scales are set by transistors. The energy scaling challenges of transistors can be attributed to simultaneously meeting high current density, high current/impedance modulation, and the inability to lower voltages. Hence, a new logic element that lowers the voltage and charge needs is a priority, not only for lowering logic power but also memory access power. Here, we propose a novel 3-terminal logic element for low energy computing, a solid-state transcapacitor (TCAP). A TCAP is a solid state displacement current modulator realized by a gate which controls the charge-voltage relationship of the channel. Unlike transistors, TCAPs eliminate the dissipative transport current, are not bound by the Boltzmann current modulation limit, and operate with displacement currents limited only by the polarization response and contact resistance. Hence, TCAP circuits may simultaneously overcome the voltage, current density, and current modulation limits of CMOS. We describe a solid state TCAP using a piezoelectric transcapacitor in which a gate-controlled stressor modulates the capacitance of a polar channel via electromechanical coupling. This device achieves inversion and gain, essential for logic, and is functionally equivalent to a 1T-1C memory cell, enabling dense memory. Using voltage scaling, capacitive energy recovery, and high polarization densities of polar materials, the logic based on TCAP offers a pathway to 100 fold lower energy consumption with a delay comparable to ultimately scaled CMOS devices. This approach provides a new potential pathway for low-energy computing beyond the limits of transistors using electro-mechanics and multiferroics.

In the framework of the Keldysh formalism and the tight-binding model, we investigate spin-orbit phenomena such as the anomalous and spin Hall effects, tunneling anisotropic magnetoresistance, and Rashba-induced spin-orbit torque in single-barrier tunnel junctions. We focus on two configurations: one with a ferromagnetic metal [normal metal (NM)/insulator (I)/ferromagnetic metal (FM)] and the other with a ferromagnetic insulator [NM/ferromagnetic insulator (FI)/NM], both incorporating an asymmetric interfacial Rashba spin-orbit coupling. Using analytical methods and numerical simulations, we derive expressions for these spin-orbit phenomena. We find that while the anomalous Hall effect and spin-orbit torque behave similarly in both configurations, tunneling anisotropic magnetoresistance and the angular dependence of spin Hall effect are significantly enhanced by nearly an order of magnitude when a FI is used. This enhancement remains even for modest exchange splittings, suggesting that FIs such as Eu chalcogenides and spinel oxides are promising for high-efficiency spintronic applications. Additionally, we observe a sign reversal of these effects in NM/I/FM junctions as the system shifts from half-metallic to low-band-filling regimes, while no such reversal occurs in NM/FI/NM due to the spin-filtering effect of the barrier.

Interfacial engineering of magnetic anisotropy is crucial for the development of low-power spintronic memory devices. In thin-film magnetic heterostructures, perpendicular magnetic anisotropy (PMA) supports high-density data storage by reducing device dimensions while maintaining thermal stability and data retention, whereas voltage-controlled magnetic anisotropy (VCMA) facilitates energy-efficient data writing. However, achieving simultaneous optimization of PMA and VCMA is challenging due to their reliance on intricate interfacial parameters and synthesis conditions. This study presents a systematic strategy to modulate spin–orbit coupling (SOC) strength at the CoFeB/MgO interface by incorporating an iridium heavy-metal layer and precisely tuning the thickness of CoFeB and Ir. Through post-deposition annealing, we engineer the SOC to simultaneously enhance PMA and VCMA, addressing critical limitations in the design of voltage-driven magnetoresistive devices. These findings highlight the significance of interfacial tuning in improving the performance and energy efficiency of spintronic memory technologies, paving the way for their integration into next-generation data storage systems.

Adopting current-driven switching mechanisms in spintronic devices has effectively addressed the challenges of magnetic field-dependent switching and large device footprints(1, 2), thereby providing a high-density, fast, energy-efficient, and non-volatile memory solution for massive data handling3–7. The Spin-Filter Tunnel Junction (SFTJ) is emerging as an alternative spintronic device for memory applications(8, 9). However, until now, SFTJ devices have been manipulated by external magnetic fields. This paper reports the current-induced switching in the SFTJ devices, where the magnetic state of the ferromagnetic insulating manganite, Sm0.75Sr0.25MnO3 (SSMO), serving as the spin-filter barrier, is manipulated by the current. The realization of these devices involved the growth of lattice-matched oxide heterostructures and the fabrication of nanopillar tunnel devices, achieving an unconventional magnetoresistance (MR) of approximately 200% at 5K. This work highlights the strong influence of applied current on the magnetic switching field, suggesting a current-induced inverse metamagnetic transition in the ferromagnetic insulating barrier layer. Through comprehensive analysis under various experimental conditions and supported by theoretical calculations, this study presents the first demonstration of current-induced magnetic field-free switching in SFTJ devices. This marks a significant advancement in the field of spintronics, particularly at low temperatures, for energy-efficient cryogenic memory technology applicable to quantum electronics(10, 11) and quantum computing(12, 13).

Atomic-scale spectroscopic imaging of sputtered magnetic tunnel junction structures with a thick oxygen-rich MgO barrier reveals the diffusion of iron and cobalt into the MgO barrier from CoFeB electrodes. First principles calculations are performed to (1) confirm that Fe diffusion through Mg vacancies is energetically favorable, (2) quantify the reduction of interfacial perpendicular magnetic anisotropy due to Fe diffusion into MgO, and (3) predict that the presence of Fe impurities in MgO causes an increased leakage and a tunneling magnetoresistance decrease. Through the chemical shift of the Fe L3 edge and the peak ratio Fe L3/Fe L2 measured by electron energy loss spectroscopy, we suggest that, within MgO, iron with mixed oxidation state Fe2+ and Fe3+ or higher is found in the as-grown structure, which is reduced by annealing to Fe2+. These results indicate that the stoichiometry of as-deposited MgO barrier layers plays an important role in controlling the microstructure and optimizing the performance of magnetic tunnel junctions.

Spintronic devices that utilize spin transfer torque are promising for integrated memory applications. However, these devices face substantial energy consumption challenges due to the high current densities required for switching. Conversely, voltage-driven spintronic devices, using capacitive displacement charge, can realize switching operations that are energy-efficient (approximate to 1-10 fJ bit-1). This work investigates switching based on voltage control of the interlayer exchange coupling in perpendicular magnetic anisotropy (PMA) multilayered heterostructures. Unlike previous works that utilized gating techniques that employ ionic transport mechanisms to control interlayer exchange coupling, this study employs electrostatic gating by using MgO, which is more compatible with modern spintronic-based memories. These results suggest that the magnetization anisotropy, and the magnitude, and phase of the Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling function with spacer layer thickness can be controlled through electric gating, providing a promising avenue for the development of energy-efficient magnetic data storage devices. This work highlights the significant impact of electrical gating with MgO as the gate material and Ir as the spacer layer on interlayer exchange coupling (IEC) and magnetic anisotropy in perpendicular magnetic heterostructures. These findings demonstrate promising results in manipulating the strength of the IEC, while still achieving high endurance. This opens promising possibilities for the creation of voltage-controlled exchange coupling-assisted Magnetic random-access memory (MRAM) devices for low-power practical spintronic applications. image

Conventional spintronics-based memory devices use an electrical current in elegant ways to control the direction and dynamics of electrons' spin, yet at higher energy cost and lower device endurance. Therefore, keeping pace with the growing demand for faster, smaller, and ultra-low-power electronic devices, research in the field of voltage control of magnetism has intensified recently with the promises to deliver ultra-low-power operating non-volatile memory solutions for next-generation computing systems. Here, we present our recent efforts in voltage-controlled magnetism via different approaches; voltage-controlled magnetic anisotropy (VCMA), voltage-controlled exchange coupling (VCEC), and multiferroic-based magnetoelectric coupling (MEC) for spintronics applications. These studies yielded several new findings. Large tunability of perpendicular magnetic anisotropy (PMA) has been achieved with the insertion of the Pt layer at the MgO/Ferromagnet interface. The modulation of the interlayer exchange coupling with the Ru spacer layer has been demonstrated by using non-ionic liquid gating such as MgO. Besides this, we have also shown the modulation of the magnetism by utilizing the magneto-electric coupling effect in a bismuth ferrite-based multiferroic system. These efforts provide several routes to modulate the resistance states of spintronic devices at low power and bring forth a vast playground to develop next-generation energy-efficient computing devices.

Understanding of damping processes in ferromagnetic thin films at elevated temperatures has significant im-plications for heat-assisted magnetic recording, spin-transfer torque memory, and magnetic sensors operating at high temperatures. Through cavity-based high-temperature ferromagnetic resonance (FMR) measurements, this work examined the FMR linewidth and damping properties of continuous cubic FePt thin films at elevated temperatures. The data show that the FMR linewidth and the Gilbert damping constant both increase mono-tonically when temperature is increased from room temperature toward the Curie temperature. This temperature dependence is opposite to that observed previously in FePt thin films that are granular, rather than continuous, and have L10 structure, rather than cubic structure; in those films, the FMR linewidth decreases monotonically with an increase in temperature [PR Applied 10, 054046 (2018)]. These opposite results originate from the difference in the crystalline structure and microstructure of the films. In the previous work, the granular L10 -order FePt films hold dense material imperfection and thereby may host strong two-magnon scattering (TMS); the TMS-produced damping decreases with an increase in temperature, giving rise to reduced FMR linewidths at high temperatures. In the current work, the continuous cubic FePt films have much less imperfection and thereby host weak TMS, and the dominant damping mechanism is spin-flip magnon-electron scattering (SF-MES). The SF-MES process becomes stronger with an increase in temperature, giving rise to larger linewidth and higher damping at high temperatures. This work and the previous work together demonstrate that for a given thin-film material, the temperature dependence of the FMR linewidth critically relies on the structural properties of the film. They also indicate that one can engineer damping in magnetic thin films through the control of the structural properties of the films.

The perpendicular magnetic anisotropy (PMA) at magnetic transition metal/oxide interfaces is a key element in building out-of-plane magnetized magnetic tunnel junctions for spin-transfer-torque magnetic random access memory (STT-MRAM). Size downscaling renders magnetic properties more sensitive to thermal effects. Thus, understanding the temperature dependence of the magnetic anisotropy is crucial. In this work, we theoretically address the correlation between temperature dependence of PMA and magnetization in typical Fe/MgO-based structures. In particular, the possible mechanisms behind the experiments reporting deviations from the Callen and Callen scaling power law are analyzed. At ideal interfaces, first-principles calculations reveal (i) small high-order anisotropy constants compared to first order and (ii) enhanced exchange constants. Considering these two intrinsic effects in the atomistic simulations, the temperature-dependence of the total and layer-resolved anisotropy are found to follow the Callen and Callen scaling power law, thus ruling out an intrinsic microscopic mechanism underlying deviations from this law. Besides, two possible extrinsic macroscopic mechanisms are unveiled namely the influence of the dead layer, often present in the storage layer of STT-MRAM cells, and the spatial inhomogeneities of the interfacial magnetic anisotropy. About the first mechanism, we show that the presence of a dead layer tends to reduce the scaling exponents. In the second mechanism, increasing the percentage of inhomogeneity in the interfacial PMA is revealed to decrease the scaling exponent. These results allow us to explain the difference in scaling exponents relating anisotropy and magnetization thermal variations reported in earlier experiments. This is crucial for the understanding of the thermal stability of the storage layer magnetization in STT-MRAM applications.

Structural and chemical order impact magnetic properties of solids, which are governed by spin-orbit coupling and exchange interaction. The ordered L10 phase of FePt is a key material to heat-assisted magnetic recording; to enable high storage density, a solid understanding is needed of structural and chemical disorder at small length scales, as well as associated modifications of the electronic band structure. Here, we investigate the effect of boron and copper additions (≲6 mol% Cu) on structural and magnetic properties of L10 FePt granular media. Two copper-driven mechanisms, although competing, can lead to improvements in both structural and magnetic properties. In particular, the Cu substitution on the Fe-site leads to a degradation of magnetic properties due to the delocalized electron orbitals originating from a larger Cu d-orbital occupancy. At the same time, Cu substitution leads to an enhanced crystallographic order and consequently magneto-crystalline anisotropy, which offsets the former effect to a large extent. Our study is based on magnetometry, x-ray absorption spectroscopy, ab-initio calculations and a phenomenological theory of disordered FePt granular media. We do not observe a sizable modification to Fe moments and electronic configuration; Cu reveals two different resonances associated with the presence and absence of Cu-B bonds that vary with total Cu concentration.

The thermal spin torque induced by the spin-dependent Seebeck effect in double-barrier tunnel junctions is derived considering free-electron and tight-binding calculations. We show that in systems comprising ferromagnetic electrodes and nonmagnetic barriers, the in-plane component of the thermal spin torque is the dominant term, whereas in junctions comprising nonmagnetic electrodes and ferromagnetic barriers, both components, the in-plane and the out-of-plane, are comparable in magnitude. Moreover, larger torque amplitudes up to 3 orders of magnitude are obtained in the second system as a result of the spinfiltering effect; consequently, double-barrier tunnel junctions in the presence of magnetic insulators offer an enhanced thermal spin-torque mechanism for reliable applications. We propose taking advantage of quantum resonant tunneling through resonance states below the Fermi level in these structures that can pave a route toward achieving larger spin-torque efficiencies, even when considering smaller values of the exchange splitting. Furthermore, we identify the parameters needed to tune efficiently these resonant states.

Hafnia‐based ferroelectric tunnel junctions (FTJs) hold great promise for nonvolatile memory and emerging data storage applications. In this article, a large tunnel electroresistance effect with ultrathin Hf 0.5 Zr 0.5 O 2 (HZO) barrier based FTJs is reported. Robust ferroelectricity is achieved with ≈1 nm films by stabilizing the rhombohedral polar phase of HZO (R‐HZO) through a large compressive strain, induced by growing the film epitaxially on a SrTiO 3 (001) substrate. The OFF/ON ratio of the junction resistance at zero bias is about 135 with ≈1 nm thick barrier, which increases to ≈10 5 with increasing the barrier thickness to ≈2.5 nm. The resistance‐area product (RA) of tunnel junctions is reduced by nearly three orders of magnitude by using an ≈1 nm R‐HZO barrier as compared with typically reported RA values for doped‐HfO 2 barrier based FTJs, which significantly improves signal‐to‐noise ratio during the read operation. These results set the stage for further exploration of Hafnia‐based FTJs for non‐volatile memory applications.

The ongoing thrust in big data mining and artificial intelligence is critically demanding the high-density and fast access data storage, which cannot be fulfilled with current computation architecture due to the slow access speed of memory. Using the nonvolatile memory (NVM) element with high density and high speed can potentially tackle this impasse in the journey of next-generation computing [1] . Among several others, magnetic random-access memory (MRAM) is one of the promising NVM elements [2] . The basic building block of MRAM is a magnetic tunnel junction (MTJ), where the resistance state of the device can be modulated by manipulating the spin state of the magnetic layers via the current or magnetic field. Magnetization manipulation by voltage is an attractive alternative as it reduces the energy consumption by orders of magnitude with faster write/read operation and provides a higher density memory solution compared with current-controlled devices. The common route to use the voltage for this purpose is by exploiting the voltage-controlled magnetic anisotropy (VCMA) effect at the magnetic layer/ MgO interface [3] . Upon the application of voltage, the modification of the electronic occupation states of the d orbitals of the ferromagnetic electrode at the interface modulates the magnetic anisotropy. Additionally, the electric field-induced magnetic dipole moment and the Rashba effect are also proposed mechanisms for the origin of the VCMA effect [4] . In addition to the large VCMA effect for the writing operation, high perpendicular magnetic anisotropy (PMA) is required for thermal stability of data retention in MRAM devices [5] . The enhancement in PMA and VCMA effect in the CoFe/MgO system has resulted from the insertion of a thin metallic dusting layer (e.g. Ir, Mg, Pd, Hf) at the CoFe/MgO interface but at the expense of reducing magnetic moment [6] . In this work, we have demonstrated a large enhancement in PMA, the coercive field of the CoFe layer, and the VCMA effect with the insertion of thin, novel metallic dusting layers between CoFe and MgO layers without any reduction in magnetic moment. These results demonstrate that the engineering of the ferromagnet/MgO interface with the insertion of a suitable metallic dusting layer can provide a pathway to develop high-density voltage-driven spintronic devices.

Broadband ferromagnetic resonance (FMR) and high-temperature (T) FMR measurements are carried out to study interlayer exchange coupling (IEC) in a magnetic hard-soft bilayered system where the hard layer is a FePt thin film with strong perpendicular anisotropy and the soft layer is a thin film made of Fe, Co, or their alloys. The data indicate that the effective exchange field (H-ex) produced by the IEC on the soft layer increases with a decrease in the thickness or saturation induction (4 pi M-s) of the soft layer. With an increase in T, H-ex drops by an amount larger than 4 pi M-s. The effective damping constant of the soft layer increases with H ex and can vary by two orders of magnitude. In samples with H-ex > 4 pi M-s, the damping constant is insensitive to the choice of material of the soft layer. In samples with H ex < 4 pi M-s, the damping constant strongly depends on the choice of material. When T is increased from room temperature to the Curie temperature of the hard layer, the FMR linewidth drops significantly in samples where H-ex is relatively large, but remains constant or even increases slightly at high T in samples where H-ex is very small. The effects of H-ex on the damping and linewidth can be understood by considering two distinct components in the overall damping, an intrinsic component mainly due to spin-flip magnon-electron scattering and an extrinsic component due to IEC-associated spin pumping at the interface.

Realization of sub‐10 nm spin‐based logic and memory devices relies on the development of magnetic materials with perpendicular magnetic anisotropy that can provide low switching current and large thermal stability simultaneously. In this work, the authors report on one promising candidate, Fe16N2, a heavy‐metal‐free, non‐interface perpendicular magnetic material and demonstrate a perpendicularly magnetized current‐perpendicular‐to‐plane (CPP) giant magnetoresistance (GMR) device based on Fe16N2. The crystalline‐based perpendicular anisotropy of Fe16N2 in the CPP GMR device is measured to be about 1.9 × 106 J m−3 (1.9 × 107 erg cm−3), which is sufficient to maintain the thermal stability of sub‐10 nm devices. A first principle calculation is performed to support this large magnitude of the perpendicular anisotropy. Moreover, the Gilbert damping constant of the Fe16N2 thin film (α ≈0.01) measured by ferromagnetic resonance (FMR) is lower than for most existing materials with crystalline perpendicular magnetic anisotropy. The non‐interface perpendicular anisotropy and low damping properties of Fe16N2 may offer a pathway for future spintronics logic and memory devices.

Sequencing DNA modifications and lesions, such as methylation of cytosine and oxidation of guanine, is even more important and challenging than sequencing the genome itself. The traditional methods for detecting DNA modifications are either insensitive to these modifications or require additional processing steps to identify a particular type of modification. Transverse-current sequencing in nanopores can potentially identify the canonical bases and base modifications in the same run. In this work, we demonstrate that the most common DNA epigenetic modifications and lesions can be detected with any predefined accuracy based on their tunneling current signature. Our results are based on simulations of the nanopore tunneling current through DNA molecules, calculated using nonequilibrium electron-transport methodology within an effective multiorbital model derived from first-principles calculations, followed by a base-calling algorithm accounting for neighbor current-current correlations. This methodology can be integrated with existing experimental techniques to improve base-calling fidelity.

High-temperature ferromagnetic resonance (FMR) in FePt-based media materials is studied for the first time. The FMR linewidth (Delta H) as a function of temperature (T), field angle (theta(H)), and the volume fraction (x) of carbon in the material is determined, and the effective Gilbert damping constant and the Bloch-Bloembergen relaxation time are estimated. The data suggest that at temperatures 10-45 K below the Curie temperature, two-magnon scattering and spin-flip magnon-electron scattering make comparable contributions to Delta H. With a decrease in T, Delta H increases due to enhancement of the two-magnon scattering. Delta H can be tuned via varying x and shows a maximum at theta(H) approximate to 45 degrees when varying theta(H).