Interface-induced superconductivity has recently been achieved by stacking a magnetic topological insulator layer on an antiferromagnetic FeTe layer. However, the mechanism driving this emergent superconductivity remains unclear. Here, we employ molecular beam epitaxy to grow a 1T-CrTe2 layer, a 2D ferromagnet with a Curie temperature up to room temperature, on a FeTe layer. These 1T-CrTe2/FeTe heterostructures show superconductivity with a critical temperature of ∼12 K. Through magnetic force microscopy measurements, we observe the Meissner effect on the surface of the 1T-CrTe2 layer. Our electrical transport measurements reveal that the 1T-CrTe2/FeTe heterostructures exhibit nonreciprocal charge transport behavior, characterized by a large magneto-chiral anisotropy coefficient. The enhanced nonreciprocal charge transport in 1T-CrTe2/FeTe heterostructures provides a promising platform for exploring the magnetically controllable superconducting diode effect.

The unusual transport properties of strange metals point to the breakdown of the quasiparticle picture, the understanding of which remains one of the most vexing problems in physics. Here, we report investigations of the electrical Hall effect of the strange metal superconductor BaFe_2(As_1-xP_x)_2. We show that a doping-independent contribution to the Hall effect exists within a fan shaped region above a putative quantum critical point. This `strange metal Hall' contribution echoes many of the properties of the antiferromangetic Hall response, but attains universal properties that distinguish it from the effects of Fermi surface reconstruction. This is consistent with an underlying origin connected to the presence of critical fluctuations, tying it to observations of T-linear resistivity and the appearance of unconventional superconductivity.

Low dimensional crystallographic motifs have long been associated with desirable physical properties. The confinement of electrons to low dimensions is thought to enhance quantum fluctuations and may promote correlated phenomena. Here, using the antagonistic pair concept, we add Y to the immiscible Co-Ag pair to discover Y_4Co_3Ag. This compound adopts a monoclinic I2/m structure consisting of Y channels that are filled by one-dimensional zigzag and hexagonal Co chains, which extend along the crystallographic b-axis with no nearest neighbor contacts between Co and Ag atoms. Transport, magnetic, and specific heat measurements reveal that Y_4Co_3Ag orders antiferromagnetically at T_N=14.9 K with an effective magnetic moment μ_eff = 1.4 μ_B/Co. Specific heat measurements show only a small entropy loss on the order of 0.1 Rln2 associated with magnetic order, and magnetization isotherms, in DC fields up to 70 kOe at 1.8 K and in pulsed fields up to 600 kOe at 500 mK, indicate a small ordered moment of less than 0.2 μ_B/Co. Taken together, our results imply the presence of small, itinerant moments and strong fluctuations in Y_4Co_3Ag, suggesting that Y_4Co_3Ag may be a promising candidate material to investigate itinerant magnetic interactions in a quasi-one dimensional system.

Scaling behavior in magnetization has been reported in a wide range of quantum spin liquid (QSL) candidates and is often interpreted as evidence for scale-free spin liquid physics. Here we present a comprehensive scaling analysis of high-field magnetization measurements on the QSL material YbZn_2GaO_5. Between 5 K and 70 K, M(H) displays scale invariance resembling that of a zero-field quantum critical point. Below 3 K, we observe a breakdown of this scale invariance that cannot be recovered by simply changing the critical exponents. This temperature coincides with the onset of enhanced spin correlations observed in μSR measurements. Moreover, the form of the deviation from scaling is consistent with collective spinon excitations coupled via emergent gauge interactions. These results indicate that the breakdown of scaling reflects the emergence of intrinsic low-energy excitations upon entering the QSL regime. Our work clarifies that magnetic scaling is associated with quantum critical fluctuations rather than with the spin liquid phase itself, and establishes magnetization scaling as a sensitive thermodynamic probe of emergent energy scales in QSL systems.

The magnetic structure of a magnetic topological semimetal EuMnSb_2 is investigated in fields up to 30 T using polarized and unpolarized neutron diffraction, pulsed-field x-ray magnetic circular dichroism and pulsed-field magnetometry. We determine the zero-field magnetic structures of the Eu and Mn sublattices, and find that magnetic transitions induced by applied fields below 2 T correspond to changes in the magnetic order of the Eu spins alone without detectable perturbation to the order of the Mn spins. An additional magnetic transition is observed at fields close to the saturation field for the Eu spins. We present a mean-field model which describes key features of the magnetic behavior and allows us to estimate the dominant Eu–Eu and Eu–Mn exchange interactions responsible for the coupling between magnetism and electronic topology.

Fractional magnetization plateaus provide a sensitive probe of many-body spin states in frustrated quantum magnets, yet their microscopic origin in kagome antiferromagnets remains unresolved. This is particularly true of the mysterious 1/9 plateau, which is predicted by theory but infrequently observed in experiment. Here, we investigate this problem in the S = 1/2 anisotropic kagome antiferromagnet Y-kapellasite, Y_3Cu_9(OH)_19Cl_8, using pulsed-field magnetization measurements on single crystals and high-field ^35Cl NMR. We identify a hierarchy of field-induced fractional features, including 1/3 and 1/9 plateaus, as well as a weaker low-field feature. Analysis of the NMR spectra and the magnetic susceptibility across the 1/9 plateau demonstrate that it is accompanied by an ordered local spin configuration, a strong suppression of low-energy spin fluctuations and activated behavior, consistent with a gapped fractional state. These features differ from those in the only other material YCu_3(OH)_6Br_2[Br_1-y(OH)_y] in which this plateau is observed, implying a surprising robustness of the 1/9 state to the details of the underlying magnetism.

Diverse quantum phenomena have been observed in TSn4transition metal (T) stannides, including superconductivity, nontrivial topology, and large magnetoresistance (MR) at low temperatures. Here, we report the experimental and theoretical investigation of tetragonalβ-IrSn4(space groupI41/acd) with the lattice parametersa= 6.362(3) Å andc= 22.723(0) Å. The temperature dependence of the electrical resistivity indicates thatβ-IrSn4is a good metal with Fermi-liquid behavior above the superconducting transition atTc∼ 0.7 K. Magnetic susceptibility measurements indicate it is non-magnetic. However, positive transverse MR with linear field dependence is observed. AtT= 2 K andΜ0H= 14 T, the MR reaches 700% without sign of saturation. Shubnikov-de Haas oscillations are observed from proximity detector oscillator measurements up to 60 T. We experimentally extract several frequencies, and through comparison to first-principles calculations, identify corresponding electronic bands. ForH//c, two strong oscillations,F1≈ 109 andF2≈ 302 T, allow us to determine effective masses 0.266m0and 0.300m0(m0is the free-electron mass), respectively. The topology of these bands is discussed.

The field-dependent magnetization of UTe_2 was measured through the metamagnetic transition at a variety of field angles, tracking how the step in magnetization evolves with fields tilted away from the b axis. For fields oriented within the ab plane, jumps in both M_a and M_b vanish approximately 18° away from the b axis. From contactless conductivity measurements, we find that the halo-like high-field superconducting region extends to the ab plane, where it exists only within a very narrow (<1°) angular range near the termination of the metamagnetic phase boundary and extends beyond the highest measured field of 73 T. As the field orientation tilts towards the c axis, the superconducting and metamagnetic phase boundaries no longer coincide and exhibit distinct trends.

Van der Waals antiferromagnets provide a route to thickness-controlled magnetic order, but few combine high-temperature Ising order with conducting, correlated, and topological electronic structure. Here we show that UOTe realizes this combination. Magnetic susceptibility reveals a strongly anisotropic paramagnetic response, while neutron diffraction establishes c-axis antiferromagnetic order below T_N ≃ 150 K with an order-parameter exponent β= 0.14, close to the two-dimensional Ising value. Torque magnetometry further shows that the ordered state remains well described by a uniaxial antiferromagnet below the high-field transition. Pulsed-field magnetization up to 73 T shows that the ordered state survives to very large fields applied along the c axis before entering a broad metamagnetic regime that begins near 50 T, and remains unsaturated at the highest measured field. Angle-dependent proximity detector oscillator measurements show that the metamagnetic instability is set by the field component along the ordered moment direction, providing direct evidence for Ising-like field rigidity. UOTe therefore establishes a field-rigid Ising antiferromagnet with giant spin-flip fields in a compensated Van der Waals metal, where high-temperature c-axis order, quasi-two-dimensional magnetic criticality, Kondo-associated uranium 5f hybridization, metallic transport, and symmetry-enabled topology coexist in a single material.

Diverse quantum phenomena have been observed in TSn 4 transition metal ( T ) stannides, including superconductivity, nontrivial topology, and large magnetoresistance (MR) at low temperatures. Here, we report the experimental and theoretical investigation of tetragonal β -IrSn 4 (space group I 4 1 / acd ) with the lattice parameters a = 6.362(3) Å and c = 22.723(0) Å. The temperature dependence of the electrical resistivity indicates that β -IrSn 4 is a good metal with Fermi-liquid behavior above the superconducting transition at T c ∼ 0.7 K. Magnetic susceptibility measurements indicate it is non-magnetic. However, positive transverse MR with linear field dependence is observed. At T = 2 K and Μ 0 H = 14 T, the MR reaches 700% without sign of saturation. Shubnikov–de Haas oscillations are observed from proximity detector oscillator measurements up to 60 T. We experimentally extract several frequencies, and through comparison to first-principles calculations, identify corresponding electronic bands. For H // c , two strong oscillations, F 1 ≈ 109 and F 2 ≈ 302 T, allow us to determine effective masses 0.266 m 0 and 0.300 m 0 ( m 0 is the free-electron mass), respectively. The topology of these bands is discussed.

We report a high-field thermodynamic study of the hyperhoneycomb Kitaev material β-Li_2IrO_3, using magnetotropic susceptibility to resolve its low-temperature field-angle phase diagram across the principal crystallographic planes in magnetic fields up to 60 T. Rather than evolving directly from the low-field incommensurate state into a polarized regime, the system exhibits a strongly direction-dependent sequence of correlated phases. Most notably, for fields in the ac-plane, we identify an additional high-field phase that is absent in the other principal planes and exists only within a restricted region of field-angle space. This phase structure is naturally explained by the competition between magnetic field and bond-directional exchange interactions. Using a symmetry-based description supported by microscopic calculations within the J-K-Γ model, we show that off-diagonal Γ exchange couples the ferromagnetic and staggered magnetic orders and thereby stabilizes the observed correlated high-field phases. The measured angular dependence of the critical fields is quantitatively captured by this theory, identifying Γ exchange as the key interaction controlling the high-field response. These results clarify why the promise of a field-induced spin liquid – the notion that suppressing magnetic order might reveal the underlying Kitaev physics – remains unfulfilled in candidate materials: even when the Kitaev interaction is large, off-diagonal exchange stabilizes symmetry-constrained correlated phases that instead preempt the polarized state.

HfCuSi2-type pnictogen compounds have recently been shown to be a versatile platform for designing materials with topologically nontrivial band structures. However, these phases require strict control over the electron count to tune the Fermi level, which can only be achieved in compositions with A2+M2+Pn2 and A3+M+Pn2 (A = lanthanides, M = transition metals, Pn = pnictogens P-Bi) charge distribution. While such lanthanide compounds have been thoroughly studied as candidate magnetic topological materials, their heavy element analogs with uranium and bismuth remain largely underexplored. In this report, we present the synthesis of UCuxBi2 single crystals and study their magnetic properties. Detailed structural analysis revealed that flux-grown crystals always form as a site-deficient UCuxBi2 composition, where x varies between 0.20 and 0.64. Magnetic property measurements revealed a dependence of the magnetic coupling on the Cu site deficiency, linearly changing the Néel temperature from 51 K for UCu0.60Bi2 to 118 K for UCu0.30Bi2. Moreover, higher Cu concentration promotes a metamagnetic transition in highly magnetically anisotropic UCu0.60Bi2 single crystals. We show that DFT calculations can successfully model site deficiency in the UCuxSb2 and UCuxBi2 systems. This work paves the way toward using the site deficiency to tune the Fermi level in more ubiquitous A3+M2+xPn2 phases, which previously have not been considered topological candidate materials due to unfavorable electron count.

TbV_6Sn_6 is a topological metal where ferromagnetic Tb ions with strong uniaxial magnetic anisotropy interact with V kagome layers. Inelastic neutron scattering (INS) measurements show that the Tb ions adopt an Ising doublet ground state. Here, we consider whether a transverse magnetic field can drive TbV_6Sn_6 toward a quantum critical point, providing a rare example of transverse-field Ising criticality in a metallic compound. High-field magnetization measurements reveal a first-order-like spin-reorientation transition at 25.6 T. Our INS-based magnetic model finds that this is caused by an avoided crossing of an excited-state singlet with the ground-state doublet. Surprisingly, our model predicts that quantum critical and tricritical points are accessible within the range of experimentally determined model parameters and may be reached by varying the direction of an applied magnetic field.

The quantum spin liquid is a state manifesting extraordinary many-body entanglement, and the material NaYbSe2 is thought to be one of the most promising candidates for its realization. Through lowtemperature heat capacity and thermal conductivity measurements, we identify an apparent contradiction familiar to many quantum spin liquid candidates: While entropy is stored by apparently gapless excitations, the itinerant carriers of entropy are gapped. By studying the compositional series NaYbxLu1-xSe2 across a percolation transition of the magnetic lattice, we suggest that this contradiction can be resolved by the presence of entanglement scales of random sizes. Moreover, as we truncate the scale of entanglement by magnetic dilution, we show that the itinerant magnetic entropy carrier in NaYbSe2 does not arise from a uniform globally entangled spin ground state but rather materializes through the stochastic propagation of boundaries between locally entangled spin objects.

We report on the thermodynamic and transport properties of the rare-earth Zintl compound Eu5Sn2As6, which orders as a canted antiferromagnetic semiconductor at 10.3 K. The system also displays a complex cascade of magnetic phases arising from geometric and magnetic exchange frustration, with high sensitivity to the application and direction of small magnetic fields. At low temperature, Eu5Sn2As6 exhibits negative colossal magnetoresistance of up to a factor of 6000. This represents a lower bound as the conductivity appears to be shunted by an unknown conduction channel, causing the resistivity to saturate. Mechanisms for the low-temperature saturation of resistivity are discussed.

The magnetic properties and phase diagrams of S = 1/2 quasi-one-dimensional Heisenberg antiferromagnets are well-established with copper-containing coordination polymers as the platform of choice due to their low energy scales and ease of chemical substitution. The inability to uncover orbitally resolved components of the magnetization has, however, been a long-standing barrier to greater understanding of high field spin state transitions. In this work, we combine pulsed field magnetization, optical spectroscopy, and magnetic circular dichroism with complementary electronic structure calculations to unravel orbital-specific contributions to the magnetism in the linear chain quantum magnet [CuL2(H2O)2(pyz)](ClO4)2 [L = 5-methyl-2-pyridone; pyz = pyrazine]. In addition to revealing a spin flop and field-driven transition to the fully saturated spin state, we untangle the green → teal color change across the 185 K structural phase transition and employ what we learn about the different Cu2+ → pyrazine charge transfer excitations to decompose the magnetic circular dichroism. Analysis reveals that both eg-derived Cu2+ 3d orbitals play a role in the field-driven transition to the fully saturated state, not just those formally hosting unpaired electrons. We attribute the surprisingly strong dichroic signature at room temperature to the presence of uncorrelated spin.

In metals, electrons in a magnetic field undergo cyclotron motion, leading to oscillations in physical properties called quantum oscillations. This phenomenon has never been seen in a robust insulator because there are no mobile electrons. We report an exception to this rule. We study a Mott insulator on a kagome lattice which does not order magnetically down to milli-Kelvin temperatures despite antiferromagnetic interactions. We observe a plateau at magnetization equal to 1 9 Bohr magneton per magnetic ion, accompanied by oscillations in the magnetic torque, reminiscent of quantum oscillations in metals. The temperature dependence obeys Fermi distribution. These phenomena are consistent with a quantum spin liquid state whose excitations are fermionic spinons with a Dirac-like spectrum coupled to an emergent gauge field.

YbZn_{2}GaO_{5} is a promising candidate for realizing a quantum spin liquid (QSL) state, particularly owing to its lack of significant site disorder. Pulsed-field magnetometry at 0.5 K shows magnetization saturating near 15 T, with a corrected saturation moment of 2.1(1)μ_{B} after subtracting the van Vleck contribution. Our zero-field μSR measurements down to milliKelvin temperatures provide evidence for a dynamic ground state and the absence of magnetic order. To probe fluctuations in the local magnetic field at the muon site, we performed longitudinal field μSR experiments. These results provide evidence for spin dynamics with a field dependence that is consistent with a U1A01 Dirac quantum spin liquid as a plausible description of the ground state.

The heavy fermion material UTe 2 is a candidate topological superconductor that exhibits multiple magnetic field–induced superconducting phases. One such phase exists only at fields greater than 40 tesla, a considerable scale given its critical temperature of only 2 K. Here, we extend measurements of this state with fields outside of the bc crystallographic plane and reveal its core structure: The superconducting phase wraps around the b axis in a halo-like fashion and appears to be stabilized by a field component perpendicular to the magnetic easy axis. This angle dependence points to a multicomponent spin-triplet order parameter with a finite angular momentum of the Cooper pairs. The pairing mechanism remains enigmatic, and UTe 2 ’s specific magnetophilic superconducting tendencies seem incompatible with existing models for field-enhanced superconductivity.

We observe magnetic quantum oscillations in the heat capacity of the Kondo insulator YbB_{12}. The frequency of these oscillations, F=700  T, agrees with that from magnetoresistance and torque magnetometry experiments for μ_{0}H>35  T in the Kondo insulating phase. Remarkably, the quantum-oscillation amplitudes in the heat capacity are substantial, with ΔC[over ˜]/T≈0.5  mJ mol^{-1} K^{-2} at 0.8 K, accounting for 13% of the known linear heat-capacity coefficient γ. Double-peak structures of quantum-oscillation amplitudes due to the distribution function of fermions were identified and used to determine the value of the effective mass from the heat capacity, which agrees well with that from torque magnetometry. These observations support bulk charge-neutral fermions contributing to the quantum oscillations in YbB_{12}.