Orbital selective commensurate modulations of the local density of states in ScVSn probed by nuclear spins.

The kagome network is a unique platform that harbors a diversity of special electronic states due to its inherent band structure features comprising Dirac cones, van Hove singularities, and flat bands. Some kagome-based metals have recently been found to exhibit favorable properties, including superconductivity, charge order, and signatures of an anomalous Hall effect. The kagome system ScVSn is a promising candidate for studying the emergence of an unconventional charge order and accompanying effects.

Observation of the Anomalous Hall Effect in a Layered Polar Semiconductor.

Progress in magnetoelectric materials is hindered by apparently contradictory requirements for time-reversal symmetry broken and polar ferroelectric electronic structure in common ferromagnets and antiferromagnets. Alternative routes can be provided by recent discoveries of a time-reversal symmetry breaking anomalous Hall effect (AHE) in noncollinear magnets and altermagnets, but hitherto reported bulk materials are not polar. Here, the authors report the observation of a spontaneous AHE in doped AgCrSe , a layered polar semiconductor with an antiferromagnetic coupling between Cr spins in adjacent layers.

Electron spin resonance study on the 4honeycomb quantum magnet YbCl.

The local magnetic properties of Ybin the layered honeycomb material YbClwere investigated by electron spin resonance on single crystals. For in-plane and out-of-plane field orientations the-factor shows a clear anisotropy (g∥=2.97(8)andg⊥=1.

Field-Tunable Berezinskii-Kosterlitz-Thouless Correlations in a Heisenberg Magnet.

We report the manifestation of field-induced Berezinskii-Kosterlitz-Thouless (BKT) correlations in the weakly coupled spin-1/2 Heisenberg layers of the molecular-based bulk material [Cu(pz)_{2}(2-HOpy)_{2}](PF_{6})_{2}. At zero field, a transition to long-range order occurs at 1.38 K, caused by a weak intrinsic easy-plane anisotropy and an interlayer exchange of J^{'}/k_{B}≈1  mK.

Gapless Quantum Spin Liquid in the Triangular System Sr_{3}CuSb_{2}O_{9}.

We report gapless quantum spin liquid behavior in the layered triangular Sr_{3}CuSb_{2}O_{9} system. X-ray diffraction shows superlattice reflections associated with atomic site ordering into triangular Cu planes well separated by Sb planes. Muon spin relaxation measurements show that the S=1/2 moments at the magnetically active Cu sites remain dynamic down to 65 mK in spite of a large antiferromagnetic exchange scale evidenced by a large Curie-Weiss temperature θ_{CW}≃-143  K as extracted from the bulk susceptibility.

Signatures of a Spin-1/2 Cooperative Paramagnet in the Diluted Triangular Lattice of Y_{2}CuTiO_{6}.

We present a combination of thermodynamic and dynamic experimental signatures of a disorder driven dynamic cooperative paramagnet in a 50% site diluted triangular lattice spin-1/2 system: Y_{2}CuTiO_{6}. Magnetic ordering and spin freezing are absent down to 50 mK, far below the Curie-Weiss scale (-θ_{CW}) of ∼134  K. We observe scaling collapses of the magnetic field and temperature dependent magnetic heat capacity and magnetization data, respectively, in conformity with expectations from the random singlet physics.

Impact of inversion symmetry on a quasi-1D S = 1 system.

Here, we report the synthesis and magnetic properties of a novel, centrosymmetric, quasi-1D spin chain system LaVWSO, with hexagonal crystal structure (P6/m, a  =  9.460 76(3), c  =  5.518 09(2) Å).

Evolution from Ferromagnetism to Antiferromagnetism in Yb(Rh_{1-x}Co_{x})_{2}Si_{2}.

Yb(Rh_{1-x}Co_{x})_{2}Si_{2} is a model system to address two challenging problems in the field of strongly correlated electron systems. The first is the intriguing competition between ferromagnetic (FM) and antiferromagnetic (AFM) order when approaching a magnetic quantum critical point (QCP). The second is the occurrence of magnetic order along a very hard crystalline electric field (CEF) direction, i.

Electron spin resonance on the spin-1/2 triangular magnet NaYbS.

The delafossite structure of NaYbS contains a planar spin-1/2 triangular lattice of Yb ions and features a possible realisation of a quantum spin-liquid state. We investigated the Yb spin dynamics by electron spin resonance (ESR) in single-crystalline samples of NaYbS. Very clear spectra with a well-resolved and large anisotropy could be observed down to the lowest accessible temperature of 2.

On Fe-Fe Dumbbells in the Ideal and Real Structures of FeGa.

The intermetallic phase FeGa belongs to the rare examples of substances with transition metals where semiconducting behavior is found. The necessary electron count of 17 ve/fu can be formally derived from eight Fe-Ga and one Fe-Fe two-center-two-electron bond. The situation is reminiscent of the well-known Fe(CO) scenario, where a direct Fe-Fe two-center-two-electron bond was shown to not be present.

Resonant torsion magnetometry in anisotropic quantum materials.

Unusual behavior in quantum materials commonly arises from their effective low-dimensional physics, reflecting the underlying anisotropy in the spin and charge degrees of freedom. Here we introduce the magnetotropic coefficient k = ∂F/∂θ, the second derivative of the free energy F with respect to the magnetic field orientation θ in the crystal. We show that the magnetotropic coefficient can be quantitatively determined from a shift in the resonant frequency of a commercially available atomic force microscopy cantilever under magnetic field.

Magnetic resonance as a local probe for kagomé magnetism in Barlowite Cu(OH)FBr.

Temperature- and field-dependent H-, F-, and Br-NMR measurements together with zero - field Br-NQR measurements on polycrystalline samples of barlowite, Cu(OH)FBr are conducted to study the magnetism and possible structural distortions on a microscopic level. The temperature dependence of the Br-NMR spin-lattice relaxation rates 1/T indicate a phase transition at T [Formula: see text] 15 K which is of magnetic origin, but with an unusually weak slowing down of fluctuations below T. Moreover, 1/TT scales linear with the bulk susceptibility which indicates persisting spin fluctuations down to 2 K.

Spin dynamics of FeGa Ge studied by electron spin resonance.

The intermetallic semiconductor FeGa acquires itinerant ferromagnetism upon electron doping by a partial replacement of Ga with Ge. We studied the electron spin resonance (ESR) of high-quality single crystals of FeGa Ge for x from 0 up to 0.162 where ferromagnetic order is observed.

Emergent Weyl Fermion Excitations in TaP Explored by ^{181}Ta Quadrupole Resonance.

The ^{181}Ta quadrupole resonance [nuclear quadrupole resonance (NQR)] technique is utilized to investigate the microscopic magnetic properties of the Weyl semimetal TaP. We find three zero-field NQR signals associated with the transition between the quadrupole split levels for Ta with I=7/2 nuclear spin. A quadrupole coupling constant, ν_{Q}=19.

Thermopower and thermal conductivity in the Weyl semimetal NbP.

The Weyl semimetal NbP exhibits an extremely large magnetoresistance and an ultra-high mobility. The large magnetoresistance originates from a combination of the nearly perfect compensation between electron- and hole-type charge carriers and the high mobility, which is relevant to the topological band structure. In this work we report on temperature- and field-dependent thermopower and thermal conductivity experiments on NbP.

Complex magnetic order from multiple Ce-sites in CePdSn.

Polycrystalline [Formula: see text] [Formula: see text] [Formula: see text] samples were synthesized by arc-melting and subsequent annealing at 970 K. Specific heat, electrical resistivity and magnetic susceptibility measurements are performed over a wide range in temperature and provide hints for the presence of a complex magnetic ordering below 3 K arising from three crystallographically independent Ce sites. This behaviour is driven by a complex interplay between ferro-, ferri-, and antiferromagnetic correlations among the Ce atoms.

Absence of low energy magnetic spin-fluctuations in isovalently and aliovalently doped LaCo2B2 superconducting compounds.

Magnetization, resistivity and (11)B, (59)Co NMR measurements have been performed on the Pauli paramagnet [Formula: see text], and the superconductors [Formula: see text] ([Formula: see text] K) and [Formula: see text] ([Formula: see text] K). The site selective NMR experiment reveals the multiband nature of the Fermi surface in these systems. The temperature independent Knight shift and 1/T 1 T clearly indicate the absence of correlated low energy magnetic spin-fluctuations in the normal state, which is in contrast to other Fe-based pnictides.

Negative magnetoresistance without well-defined chirality in the Weyl semimetal TaP.

Weyl semimetals (WSMs) are topological quantum states wherein the electronic bands disperse linearly around pairs of nodes with fixed chirality, the Weyl points. In WSMs, nonorthogonal electric and magnetic fields induce an exotic phenomenon known as the chiral anomaly, resulting in an unconventional negative longitudinal magnetoresistance, the chiral-magnetic effect. However, it remains an open question to which extent this effect survives when chirality is not well-defined.

Spin Liquid State in the 3D Frustrated Antiferromagnet PbCuTe_{2}O_{6}: NMR and Muon Spin Relaxation Studies.

PbCuTe_{2}O_{6} is a rare example of a spin liquid candidate featuring a three-dimensional magnetic lattice. Strong geometric frustration arises from the dominant antiferromagnetic interaction that generates a hyperkagome network of Cu^{2+} ions although additional interactions enhance the magnetic lattice connectivity. Through a combination of magnetization measurements and local probe investigations by NMR and muon spin relaxation down to 20 mK, we provide robust evidence for the absence of magnetic freezing in the ground state.

On the nature of superconductivity in the anisotropic dichalcogenide NbSe2{CoCp2}x.

We present a detailed study of the superconducting properties of the weakly pinned, quasi-two-dimensional superconductor 2H-NbSe2, and its intercalated variant NbSe2{CoCp2}0.26. The intercalation of 2H-NbSe2 with the organometallic donor molecule cobaltocene (CoCp2) hardly affects the superconducting properties within the layers.

Design of compensated ferrimagnetic Heusler alloys for giant tunable exchange bias.

Rational material design can accelerate the discovery of materials with improved functionalities. This approach can be implemented in Heusler compounds with tunable magnetic sublattices to demonstrate unprecedented magnetic properties. Here, we have designed a family of Heusler alloys with a compensated ferrimagnetic state.

Contiguous 3d and 4f magnetism: strongly correlated 3d electrons in YbFe2Al10.

We present magnetization, specific heat, and (27)Al NMR investigations on YbFe2Al10 over a wide range in temperature and magnetic field. The magnetic susceptibility at low temperatures is strongly enhanced at weak magnetic fields, accompanied by a ln(T0/T) divergence of the low-T specific heat coefficient in zero field, which indicates a ground state of correlated electrons. From our hard-x-ray photoemission spectroscopy study, the Yb valence at 50 K is evaluated to be 2.

Complex chiral modulations in FeGe close to magnetic ordering.

We report on detailed polarized small-angle neutron scattering on cubic FeGe in magnetic fields applied either along (transverse) the scattering vector or parallel (longitudinal) to the neutron beam. The (H, T) phase diagrams for all principal axes contain a segmented A-phase region just below the onset of magnetic order. Hexagonal Bragg-spot patterns were observed across the entire A-phase region for the longitudinal geometry.

Confinement of chiral magnetic modulations in the precursor region of FeGe.

We report on magnetic susceptibility and specific heat measurements of the cubic helimagnet FeGe in external magnetic fields and temperatures near the onset of long-range magnetic order at TC = 278.2(3) K. Pronounced anomalies in the field-dependent χac(H) data as well as in the corresponding imaginary part χ''ac(H) reveal a precursor region around TC in the magnetic phase diagram.

Interplay between Fe 3d and Ce 4f magnetism and Kondo interaction in CeFeAs(1-x)P(x)O probed by 75As and 31P NMR.

A detailed (31)P (I = 1/2) and (75)As (I = 3/2) NMR study on polycrystalline CeFeAs(1-x)P(x)O alloys is presented. The magnetism of CeFeAsO changes drastically upon P substitution on the As site. CeFePO is a heavy fermion system without long-range order whereas CeFeAsO exhibits an Fe 3d SDW type of ordering accompanied by a structural transition from tetragonal (TT) to orthorhombic (OT) structure.