Static and fluctuating magnetic moments in the ferroelectric metal LiOsO3
JPS Conference Proceedings Physical Society of Japan 日本物理学会 21:011013 (2018) 1-6
Abstract:
LiOsO3 is the first example of a new class of material called a ferroelectric metal. We performed zero-field and longitudinal-field μSR, along with a combination of electronic structure and dipole field calculations, to determine the magneticground state of LiOsO3. We find that the sample contains both static Li nuclear moments and dynamic Os electronic moments. Below ≈0.7 K, the fluctuations of the Os moments slow down, though remain dynamic down to 0.08 K. We expect this could result in a frozen-out, disordered ground state at even lower temperatures.Coupling between Spin and Charge Order Driven by Magnetic Field in Triangular Ising System LuFe2O4+delta
CRYSTALS 8:2 (2018) ARTN 88
Doping dependence of collective spin and orbital excitations in the Spin-1 quantum antiferromagnet La₂₋ₓSrₓNiO₄ oObserved by X rays.
Physical Review Letters American Physical Society 118:15 (2017) 156402
Abstract:
We report the first empirical demonstration that resonant inelastic x-ray scattering (RIXS) is sensitive to collective magnetic excitations in S=1 systems by probing the Ni L₃ edge of La₂₋ₓSrₓNiO₄ (x=0, 0.33, 0.45). The magnetic excitation peak is asymmetric, indicating the presence of single and multi-spin-flip excitations. As the hole doping level is increased, the zone boundary magnon energy is suppressed at a much larger rate than that in hole doped cuprates. Based on the analysis of the orbital and charge excitations observed by RIXS, we argue that this difference is related to the orbital character of the doped holes in these two families. This work establishes RIXS as a probe of fundamental magnetic interactions in nickelates opening the way towards studies of heterostructures and ultrafast pump-probe experiments.Spin dynamics in the antiferromagnetic phases of the Dirac metals AMnBi2 (A = Sr, Ca)
Physical Review B American Physical Society 95:13 (2017) 134405
Abstract:
The square Bi layers in AMnBi2 (A= Sr, Ca) host Dirac fermions which coexist with antiferromagnetic order on the Mn sublattice below TN=290 K (Sr) and 265 K (Ca). We have measured the spin-wave dispersion in these materials by triple-axis neutron spectroscopy. The spectra show pronounced spin gaps of 10.2(2)meV (Sr) and 8.3(8)meV (Ca) and extend to a maximum energy transfer of 61-63 meV. The observed spectra can be accurately reproduced by linear spin-wave theory from a Heisenberg effective spin Hamiltonian. Detailed global fits of the full magnon dispersion are used to determine the in-plane and interlayer exchange parameters as well as well as the magnetocrystalline anisotropy constant. To within experimental error we find no evidence that the magnetic dynamics are influenced by the Dirac fermions.Inelastic neutron scattering investigations of an anisotropic hybridization gap in the kondo insulators: CeT2 Al10 (T=Fe, Ru and Os)
Solid State Phenomena 257 (2017) 11-25