Nickel/bismuth (Ni/Bi) bilayers are a promising platform for exploring unconventional superconductivity. Ferromagnetic Ni is coupled to Bi, a strong spin orbit metal that only becomes superconducting below approx 10 mK, forming a bilayer exhibits superconductivity at a much higher temperatures, a Tc of 3 to 4 K. Such a bilayer thus makes an ideal system to probe Cooper pairing in strong spin orbit coupled magnetic environments. Magneto transport studies near Tc reveal the behavior of vortex dynamics and exchange proximity effects. It is seen that isolated vortices of the bilayers respond sensitively to out of plane fields, producing antisymmetric transverse resistance peaks attributable to competing Magnus and viscous forces. Control experiments using a ferromagnetic insulator confirm that superconductivity extends throughout the bilayer, not just confined at the interface. Overall, the results provide a unified picture of transport dominated by vortex dynamics and show that a conventional s wave order parameter accounts for the observations, with any likely unconventional contributions being only subtle.

Double hydroxide perovskites with magnetic transition-metal ions were recently identified as a unique class of materials that combine magnetic frustration with correlated proton disorder-a prerequisite for quantum-disordered fluctuating magnetic ground states resembling spin liquids. Here we present the results of muon spin relaxation (μSR) measurements carried out on fully deuterated samples of the double hydroxyperovskites CuSn(OH)6 (S = 1/2) and MnSn(OH)6 (S = 5/2) over the temperature range 0.053-50 K. The absence of any long-range magnetic order is confirmed down to 0.053 K. We observe no oscillations of the muon asymmetry down to the lowest temperature. The muon relaxation rates show a continuous increase with decreasing temperature, indicating persistent spin fluctuations in both compounds. Spin correlations are consistent with homogeneous spin dynamics. These observations reinforce the assertion that both compounds have a quantum-dynamic magnetic ground state that is consistent with a spin-liquid-like phase stabilized by proton disorder.

Among two-dimensional magnetic materials, Chromium sulphide bromide (CrSBr) has attracted considerable attention owing to its coexistence of ferromagnetic (FM) and antiferromagnetic ordering, which depends sensitively on crystallographic orientation. An additional distinguishing feature of CrSBr is its highly anisotropic Fermi surface in momentum space. In this work, we present a comprehensive investigation of magnetoresistance (MR) by systematically orienting the bias current and the applied magnetic field along all three crystallographic axes. We demonstrate that the MR serves as a direct probe of electronic anisotropy, exhibiting pronounced variations when the current is applied along different crystallographic directions under a magnetic field perpendicular to the sample plane. For in-plane magnetic fields, we observe conventional anisotropic MR accompanied by hysteresis, indicative of FM behaviour. Overall, our study provides a complete picture of electronic transport in CrSBr as a function of bias current and magnetic field orientation with respect to crystallographic directions, thereby opening pathways for future experiments requiring high sensitivity of electrical resistance to magnetic field gradients.

We report muon spin relaxation/rotation (μSR) measurements of the candidate three-dimensional (3D) quantum spin liquid (QSL) PbCuTe_2O_6, hosting S=1/2 moments, under controlled in situ [110] uniaxial compression up to σ_[110]=37.7 MPa. A small directional lattice perturbation significantly modifies the local magnetic response, while above σ_ cr∼10.8 MPa the relaxation rates are strongly enhanced and the internal-field distribution is substantially broadened. These changes occur along with the local crystalline symmetry breaking. While, no evidence for conventional static long-range magnetic order is observed, the compression drives the system towards a structurally modified and strongly correlated state in which enhanced quasi-static correlations coexist with persistent slow spin dynamics. This work demonstrates a clean and symmetry-selective route to control frustrated exchange landscape and access hidden magnetic instabilities in a 3D QSL candidate opening up the possibilities to tune other correlated systems where intrinsic coupling between magnetic and lattice degrees of freedom are relevant.

Integrating spin-dependent functionality with mainstream semiconductor technology is a central goal of modern spintronics, yet most candidate materials remain incompatible with silicon-based platforms. Here, we report the direct epitaxial integration of alpha-MnTe thin films on Si(111) via molecular beam epitaxy and demonstrate a robust anomalous Hall effect (AHE) in this silicon-compatible altermagnetic system. Despite the absence of net magnetization, the films exhibit a pronounced hysteretic Hall response, providing clear evidence of finite Berry curvature generated by symmetry breaking in the thin-film geometry. High resolution structural and spectroscopic characterization confirms phase-pure, epitaxial growth with hexagonal NiAs-type symmetry, while magnetotransport measurements reveal correlated hysteresis in both transverse and longitudinal channels with systematic temperature evolution. First-principles calculations reveal substantial uncompensated Berry curvature arising from the spin-split band structure consistent with altermagnetic symmetry and the origin of the observed Hall response. These results establish MnTe/Si(111) as a silicon-compatible altermagnetic platform and chart a concrete pathway for embedding Berry-phase-driven functionalities into scalable semiconductor device architectures.

Muon-spin-rotation (μSR) experiments and the observation of a spontaneous Nernst effect indicate time-reversal symmetry breaking (BTRS) at T_ c^ Z2 above the superconducting transition temperature T_ c in Ba_1-xK_xFe_2As_2, with x≈0.8. Further studies have pointed out that BTRS is caused by the formation of a new state of matter associated with the condensation of pairs of electron pairs. Despite exhibiting multiple unconventional effects that warrant further investigation, the electronic spectral properties of this electron quadrupling state remain largely unexplored. Here, we present detailed ^75As nuclear magnetic resonance (NMR) measurements of Ba_1-xK_xFe_2As_2, with x = 0.77, which has T_ c^ Z2 > T_ c according to measurements of the spontaneous Nernst effect. The NMR data obtained in this work provide the first direct electronic spectral characteristics of the electron quadrupling state by indicating that it evolves from a pseudogap that sets in at T^* well above T_ c^ Z2. This pseudogap behavior is consistent with μSR Knight-shift, specific-heat, and transport data indicating the formation of a bound state of electrons. According to a theory of electron quadrupling condensates, such bound-state formations should precede the onset of BTRS correlations between pairs of electron pairs. The second important insight from NMR data is the absence of spin-related magnetism. The temperature dependence of the spin-lattice relaxation rate 1/T_1T and the evolution of the NMR linewidth prove the absence of a magnetic transition at T_ c^ Z2 and rule out even a proximity to some magnetic instability. This indicates that the spontaneous magnetic fields detected in this compound are not caused by spin magnetism but are associated with persistent real-space currents.

Metallic altermagnets — distinct from conventional ferromagnets and antiferromagnets — hold potential for advanced spintronic applications. Now, experiments reveal room-temperature altermagnetism with antisymmetric spin polarization in a metallic oxide.

The cuprate superconductor La2-x Ba x CuO4 (LBCO) near x = 0.125 is a striking example of intertwined electronic orders, where 3D superconductivity is anomalously suppressed, allowing spin and charge stripe order to develop. Understanding this interplay remains a key challenge in cuprates, highlighting the necessity of external tuning for deeper insight. While in-plane uniaxial stress enhances superconductivity and suppresses stripe order, the effects of c-axis compression remains largely unexplored. Here, we use muon spin rotation (μSR) and AC susceptibility with an in situ piezoelectric stress device to investigate the spin-stripe order and superconductivity in LBCO-0.115 under c-axis compression. The measurements reveal a gradual suppression of the superconducting transition temperature (T c) with increasing c-axis stress, in stark contrast to the strong enhancement observed under in-plane stress. We further show that while in-plane stress rapidly reduces both the magnetic volume fraction (V m) and the spin-stripe ordering temperature (T so), c-axis compression has no effect, with V m and T so exhibiting an almost unchanged behavior up to the highest applied stress of 0.21 GPa. These findings demonstrate a strong anisotropy in stress response.

The present studies show that long-range magnetic order takes place in RuBr$_3$ at $\approx$ 34 K. The observations of clear oscillations in the muon time spectra demonstrate the presence of well-defined internal fields at the muon sites. The magnetic ordering appears to be very robust and static suggesting a more conventional nature of magnetic ordering in the RuBr$_3$ system at zero field. Present investigations prove that in RuBr$_3$ the Kitaev interactions are likely to be weakened at zero field in comparison to the $\alpha$-RuCl$_3$ system. This proves that it is possible to tune the Kitaev interactions by replacing Cl with heavier halogen elements such as Br.

Muon spin rotation/relaxation (mu SR) and polar Kerr effect measurements provide evidence for a time-reversal symmetry breaking (TRSB) superconducting state in Sr2RuO4. However, the absence of a cusp in the superconducting transition temperature (Tc) vs stress and the absence of a resolvable specific heat anomaly at TRSB transition temperature (TTRSB) under uniaxial stress challenge a hypothesis of TRSB superconductivity. Recent mu SR studies under pressure and with disorder indicate that the splitting between Tc and TTRSB occurs only when the structural tetragonal symmetry is broken. To further test such behavior, we measured Tc through susceptibility measurements and TTRSB through mu SR, under uniaxial stress applied along a (110) lattice direction. We have obtained preliminary evidence for suppression of TTRSB below Tc, ata rate much higher than the suppression rate of Tc.

Muon spin rotation/relaxation (μSR) and polar Kerr effect measurements provide evidence for a time-reversal symmetry breaking (TRSB) superconducting state in Sr_2RuO_4. However, the absence of a cusp in the superconducting transition temperature (T_ c) vs. stress and the absence of a resolvable specific heat anomaly at TRSB transition temperature (T_ TRSB) under uniaxial stress challenge a hypothesis of TRSB superconductivity. Recent μSR studies under pressure and with disorder indicate that the splitting between T_ c and T_ TRSB occurs only when the structural tetragonal symmetry is broken. To further test such behavior, we measured T_c through susceptibility measurements, and T_TRSB through μSR, under uniaxial stress applied along a ⟨ 110 ⟩ lattice direction. We have obtained preliminary evidence for suppression of T_TRSB below T_c, at a rate much higher than the suppression rate of T_c.

LuFe$_4$Ge$_2$ crystallizes in the ZrFe$_4$Si$_2$-type structure, hosting chains of Fe-tetrahedra giving rise to geometric frustration and low-dimensionality. The compound orders antiferromagnetically at around 36 K accompanied by a simultaneous structural transition from a tetragonal to an orthorhombic phase. The hydrostatic pressure dependence of the magnetic and structural transitions is investigated using electrical-transport, ac magnetic-susceptibility, ac calorimetry, M$\ddot{\rm o}$ssbauer, muon-spin relaxation ($\mu$SR), and x-ray diffraction measurements. External pressure suppresses the first-order transition to the antiferromagnetic phase (AFM1) around 1.8 GPa. The structural transition is largely unaffected by pressure and remains between 30 to 35 K for pressures up to 2 GPa. A second antiferromagnetic phase (AFM2) is observed at higher pressures. The transition from the paramagnetic to the AFM2 phase is of second-order nature and appears to be connected to the structural transition. The magnetic volume fraction obtained from $\mu$SR and M$\ddot{\rm o}$ssbauer measurements reveal that the entire sample undergoes magnetic ordering in both magnetic phases. In addition, similar low-temperature muon-precession frequencies in AFM1 and AFM2 phases point at similar ordered moments and magnetic structures in both phases. Our results further indicate enhanced magnetic fluctuations in the pressure induced AFM2 phase. The experimental observations together with density functional theory calculations suggest that the magnetic and structural order parameters in LuFe$_4$Ge$_2$ are linked by magnetic frustration, causing the simultaneous magneto-structural transition.

Muon spin rotation/relaxation ($\mu$SR) and polar Kerr effect measurements provide evidence for a time-reversal symmetry breaking (TRSB) superconducting state in Sr$_2$RuO$_4$. However, the absence of a cusp in the superconducting transition temperature ($T_{\rm c}$) vs. stress and the absence of a resolvable specific heat anomaly at TRSB transition temperature ($T_{\rm TRSB}$) under uniaxial stress challenge a hypothesis of TRSB superconductivity. Recent $\mu$SR studies under pressure and with disorder indicate that the splitting between $T_{\rm c}$ and $T_{\rm TRSB}$ occurs only when the structural tetragonal symmetry is broken. To further test such behavior, we measured $T_\text{c}$ through susceptibility measurements, and $T_\text{TRSB}$ through $\mu$SR, under uniaxial stress applied along a $\langle 110 \rangle$ lattice direction. We have obtained preliminary evidence for suppression of $T_\text{TRSB}$ below $T_\text{c}$, at a rate much higher than the suppression rate of $T_\text{c}$.

Physical properties of the mixed-valent tellurate of lithium and manganese, LiMn2TeO6, were investigated in measurements of ac and dc magnetic susceptibility χ, magnetization M, specific heat Cp, electron spin resonance (ESR), and nuclear magnetic resonance (NMR) in the temperature range 2–300 K under magnetic field up to 9 T. The title compound orders magnetically in two steps at T1 = 20 K and T2 = 13 K. The intermediate phase at T2 < T < T1 is fully suppressed by magnetic field µ0H of about 4 T. Besides magnetic phases transitions firmly established in static measurements, relaxation-type phenomena were observed well above magnetic ordering temperature in resonant measurements.

Background: Although rectal administration of nonsteroidal anti-inflammatory drugs is recommended as the standard pharmacologic modality to prevent postendoscopic retrograde cholangiopancreatography (ERCP) post-ERCP pancreatitis (PEP), vigorous periprocedural hydration (vHR) with lactated Ringer’s solution (LR) is emerging as an effective prophylaxis modality for PEP. There has been no head-to-head comparison between these 2. Study: This was a single-center, randomized, open-label, noninferiority, parallel-assigned, equal allocation, controlled clinical trial in a tertiary care hospital. Consecutive adults referred for ERCP, satisfying predefined inclusion criteria, underwent simple randomization and blinded allocation into 2 groups. Those allocated to vHR received intravenous LR at 3 mL/kg/h during procedure, 20 ml/kg bolus immediately afterward, and then at 3 mL/kg/h for another 8 hours. Those randomized to rectal Indomethacin received only per-rectal 100 mg suppository immediately post-ERCP. Assuming PEP of 9% in Indomethacin arm and noninferiority margin of 4%, we calculated sample size of 171 patients in each arm for 80% power and α-error 5%. Primary outcome was incidence of PEP, within 1 week, as defined by Cotton’s criteria. All analysis were done by intention-to-treat. Results: Between October, 2017 to February, 2018, 521 patients were assessed. In all, 352 were enrolled, 178 randomized to vHR, and 174 to per-rectal Indomethacin. Baseline details and ERCP outcomes were not different between 2 groups. PEP occurred in 6 (1.7%) overall, with 1 (0.6%) in hydration arm, and 5 (2.9%) in indomethacin arm; an absolute risk reduction of 2.3% (95% confidence interval: 0.9%-3.5%) and odds ratio of 0.19 (95% confidence interval: 0.02-1.65). Three patients developed severe PEP, all receiving indomethacin. Conclusions: vHR with LR is noninferior to postprocedure per-rectal Indomethacin for PEP prevention (ClinicalTrials.govID:NCT03629600).

Nematic fluctuations occur in a wide range physical systems from biological molecules to cuprates and iron pnictide high- T c superconductors. It is unclear whether nematicity in pnictides arises from electronic spin or orbital degrees of freedom. We studied the iron-based Mott insulators La 2 O 2 Fe 2 OM 2 M = (S, Se), which are structurally similar to pnictides. Nuclear magnetic resonance revealed a critical slowing down of nematic fluctuations and complementary Mössbauerr spectroscopy data showed a change of electrical field gradient. The neutron pair distribution function technique detected local C 2 fluctuations while neutron diffraction indicates that global C 4 symmetry is preserved. A geometrically frustrated Heisenberg model with biquadratic and single-ion anisotropic terms provides the interpretation of the low temperature magnetic fluctuations. The nematicity is not due to spontaneous orbital order, instead it is linked to geometrically frustrated magnetism based on orbital selectivity. This study highlights the interplay between orbital order and spin fluctuations in nematicity.

The most well-known example of an ordered quantum state—superconductivity—is caused by the formation and condensation of pairs of electrons. Fundamentally, what distinguishes a superconducting state from a normal state is a spontaneously broken symmetry corresponding to the long-range coherence of pairs of electrons, leading to zero resistivity and diamagnetism. Here we report a set of experimental observations in hole-doped Ba 1− x K x Fe 2 As 2 . Our specific-heat measurements indicate the formation of fermionic bound states when the temperature is lowered from the normal state. However, when the doping level is x ≈ 0.8, instead of the characteristic onset of diamagnetic screening and zero resistance expected below the superconducting phase transition, we observe the opposite effect: the generation of self-induced magnetic fields in the resistive state, measured by spontaneous Nernst effect and muon spin rotation experiments. This combined evidence indicates the existence of a bosonic metal state in which Cooper pairs of electrons lack coherence, but the system spontaneously breaks time-reversal symmetry. The observations are consistent with the theory of a state with fermionic quadrupling, in which long-range order exists not between Cooper pairs but only between pairs of pairs.

Discoveries of ordered quantum states of matter are of great fundamental interest, and often lead to unique applications. The most well known example -- superconductivity -- is caused by the formation and condensation of pairs of electrons. A key property of superconductors is diamagnetism: magnetic fields are screened by dissipationless currents. Fundamentally, what distinguishes superconducting states from normal states is a spontaneously broken symmetry corresponding to long-range coherence of fermion pairs. Here we report a set of experimental observations in hole doped Ba$_{1-x}$K$_x$Fe$_2$As$_2$ which are not consistent with conventional superconducting behavior. Our specific-heat measurements indicate the formation of fermionic bound states when the temperature is lowered from the normal state. However, for $x \sim 0.8$, instead of the standard for superconductors, zero resistance and diamagnetic screening, for a range of temperatures, we observe the opposite effect: the generation of self-induced magnetic fields measured by spontaneous Nernst effect and muon spin rotation experiments. The finite resistance and the lack of any detectable diamagnetic screening in this state exclude the spontaneously broken symmetry associated with superconducting two-fermion correlations. Instead, combined evidence from transport and thermodynamic measurements indicates that the formation of fermionic bound states leads to spontaneous breaking of time-reversal symmetry above the superconducting transition temperature. These results demonstrate the existence of a broken-time-reversal-symmetry bosonic metal state. In the framework of a multiband theory, such a state is characterized by quartic correlations: the long-range order exists only for {\it pairs} of fermion pairs.

The quantum spin systems ${\mathrm{Cu}}_{2}{M}^{\ensuremath{'}}{\mathrm{BO}}_{5}$ $({M}^{\ensuremath{'}}\phantom{\rule{4pt}{0ex}}=\phantom{\rule{4pt}{0ex}}\mathrm{Al},\phantom{\rule{4pt}{0ex}}\mathrm{Ga})$ with the ludwigite crystal structure consist of a structurally ordered ${\mathrm{Cu}}^{2+}$ sublattice in the form of three-leg ladders, interpenetrated by a structurally disordered sublattice with a statistically random site occupation by magnetic ${\mathrm{Cu}}^{2+}$ and nonmagnetic ${\mathrm{Ga}}^{3+}$ or ${\mathrm{Al}}^{3+}$ ions. A microscopic analysis based on density-functional-theory calculations for ${\mathrm{Cu}}_{2}{\mathrm{GaBO}}_{5}$ reveals a frustrated quasi-two-dimensional spin model featuring five inequivalent antiferromagnetic exchanges. A broad low-temperature ${}^{11}\mathrm{B}$ nuclear magnetic resonance points to a considerable spin disorder in the system. In zero magnetic field, antiferromagnetic order sets in below ${T}_{\text{N}}\ensuremath{\approx}4.1$ K and $\ensuremath{\sim}2.4$ K for the Ga and Al compounds, respectively. From neutron diffraction, we find that the magnetic propagation vector in ${\mathrm{Cu}}_{2}{\mathrm{GaBO}}_{5}$ is commensurate and lies on the Brillouin-zone boundary in the $(H0L)$ plane, ${\mathbf{q}}_{\text{m}}=(0.45,\phantom{\rule{0.16em}{0ex}}0,\phantom{\rule{0.16em}{0ex}}\ensuremath{-}0.7)$, corresponding to a complex noncollinear long-range ordered structure with a large magnetic unit cell. Muon spin relaxation is monotonic, consisting of a fast static component typical for complex noncollinear spin systems and a slow dynamic component originating from the relaxation on low-energy spin fluctuations. Gapless spin dynamics in the form of a diffuse quasielastic peak is also evidenced by inelastic neutron scattering. Most remarkably, application of a magnetic field above 1 T destroys the static long-range order, which is manifested in the gradual broadening of the magnetic Bragg peaks. We argue that such a crossover from a magnetically long-range ordered state to a spin-glass regime may result from orphan spins on the structurally disordered magnetic sublattice, which are polarized in magnetic field and thus act as a tuning knob for field-controlled magnetic disorder.