C. R. Wiebe

Gapped itinerant spin excitations account for missing entropy in the hidden-order state of URu 2 Si 2

Gapped itinerant spin excitations account for missing entropy in the hidden-order state of URu 2 Si 2

Ac susceptibility and 51V NMR study of MnV2O4

We report 51V zero-field NMR of the manganese vanadate spinel compound, MnV2O4, together with both ac and dc magnetization measurements. The field and temperature dependences of ac susceptibilities show a re-entrant-spin-glass-like behavior below the ferrimagnetic (FEM) ordering temperature. The zero-field NMR spectrum consists of multiple lines ranging from 240 to 320 MHz. Its temperature and field dependences are discussed in terms of the persistence of a small fraction of the cubic phase within the FEM ordered ground state. Due to strong spin–orbit couplings the disordered phase induces an anomalous structural and electronic state in an external field. This suggests a close correlation between magnetism and structure.

Unconventional spin glass behavior in the cubic pyrochlore Mn2Sb2O7

The new pyrochlore Mn2Sb2O7 has been synthesized via a low-temperature method to retain cubic symmetry. The resulting material has an unconventional spin glass state at TSG~41 K, in the absence of detectable site disorder or a structural phase transition. A peak in the DC susceptibility at TSG, and a characteristic shift in the real part of the AC susceptibility was noted, but with a slightly more dynamic state than predicted through the typical Mydosh spin glass parameter of ΔTSG/[TSGlog(ω)]. Time-dependent magnetization measurements show glassy behavior below 41 K. Elastic neutron scattering measurements on powder samples show significant magnetic diffuse scattering from the Mn spins beneath the transition, similar to the scattering observed in the spin liquid Tb2Ti2O7. The dynamic character of Mn2Sb2O7 is inferred to arise from the frustration inherent within the pyrochlore lattice.

Itinerant spin excitations near the hidden order transition in URu2Si2

By means of neutron scattering we show that the high temperature precursor to the hidden order state of the heavy fermion superconductor URu(2)Si(2) exhibits heavily damped incommensurate paramagnons whose strong energy dispersion is very similar to that of the long-lived longitudinal f spin excitations that appear below T(0). This suggests that there is a strongly hybridized character to the itinerant excitations observed previously above the hidden order transition. Here we present evidence that the itinerant excitations, like those in chromium, are due to Fermi surface nesting of hole and electron pockets; hence the hidden order phase probably originates from a Fermi surface instability. We identify wavevectors that span nested regions of a f-d hybridized band calculation and that match the neutron spin crossover from incommensurate to commensurate on approach to the hidden order phase.

The effect of Er doping on the multiferroics of Ho1−xErxMnO3

The magnetic phase diagram of single-crystalline Ho1−xErxMnO3 below TN (antiferromagnetic transition temperature) is determined by measuring the magnetic susceptibility (χ), specific heat (CP), and dielectric constant (e). Er doping enhances the P63cm magnetic phase above TSR (spin-reorientation temperature) and therefore decreases TSR. Er doping also reduces the P63cm phase below T2 (rare-earth element ordering temperature). The change of entropy around TSR with Er doping shows that the Er3+-ion spin is ordering at TSR. This ordering helps to narrow the P63cm to P63cm magnetic phase transition and enhance the coupling between the Ho3+/Er3+ and Mn3+ magnetic sublattices, which is shown by the dielectric constant measurements.

Two inequivalent sublattices and orbital ordering in MnV 2 O 4 studied by V 51 NMR

We report detailed

Spin dynamics of the S = 5/2 2D triangular antiferromagnet Ba3NbFe3Si2O14.

^{51}\text{V}

Magnetic field induced quantum phase transition of the S = 1 2 antiferromagnet K 2 NaCrO 8

NMR spectra in a single crystal of

Impurity-induced singlet breaking in SrCu2(BO3)2

{\text{MnV}}_{2}{\text{O}}_{4}

Surface Reconstruction of Hexagonal Y-doped HoMnO3 and LuMnO3 Studied Using Low-energy Electron Diffraction

. The vanadium spectrum reveals two peaks in the orbitally ordered state, which arise from different internal hyperfine fields at two different V sublattices. These internal fields evolve smoothly with externally applied field, and show no change in structure that would suggest a change of the orbital ordering. The result is consistent with the orbital ordering model recently proposed by Sarkar et al. [Phys. Rev. Lett. 102, 216405 (2009)] in which the same orbital that is a mixture of