44 research outputs found
The magnetic phase of the perovskite CaCrO studied with SR
We investigated the magnetic phase of the perovskite CaCrO by using the
muon spin relaxation technique accompanied by susceptibility measurements. A
thermal hysteresis loop is identified with a width of about 1 K at the
transition temperature. Within the time scale of the muon lifetime, a static
antiferromagnetic order is revealed with distinct multiple internal fields
which are experienced in the muon interstitial sites below the phase-transition
temperature, . Above , lattice deformations are indicated by
transverse-field muon-spin rotation and relaxation suggesting a magneto-elastic
mechanism.Comment: 5 pages, 4 figures. Accepted for publication in PR
The magnetic structure of the chain family NaCaVO determined by muon-spin rotation
We present muon-spin rotation measurements on polycrystalline samples of the
complete family of the antiferromagnetic (AF) chain compounds,
NaCaVO. In this family, we explore the magnetic properties
from the metallic NaVO to the insulating CaVO. We find a
critical which separates the low and high Na-concentration
dependent transition temperature and its magnetic ground state. In the
compounds, the magnetic ordered phase is characterized by a single homogenous
phase and the formation of incommensurate spin-density-wave order. Whereas in
the compounds, multiple sub-phases appear with temperature and .
Based on the muon data obtained in zero external magnetic field, a careful
dipolar field simulation was able to reproduce the muon behavior and indicates
a modulated helical incommensurate spin structure of the metallic AF phase. The
incommensurate modulation period obtained by the simulation agrees with that
determined by neutron diffraction.Comment: 7 pages, 7 figures, accepted for publication in PR
Electron localization into spin-polaron state in MnSi
Strong electron localization into a bound state has been found in both paramagnetic and ferromagnetic states of the transition metal compound MnSi by muon spin-rotation spectroscopy in magnetic fields up to 7 T and from 2 K to room temperature. This bound state, with a characteristic radius R≈0.4 nm and net spin S=24±2, is consistent with confinement of the electron’s wave function within roughly one lattice cell of MnSi and is suggested to be a spin polaron. Such spin polarons may form due to a strong exchange interaction between itinerant electrons and the magnetic electrons of Mn ions of the same 3d type; as such, they might affect the peculiar electronic and magnetic properties of MnSi
The Herbertsmithite Hamiltonian: SR measurements on single crystals
We present transverse field muon spin rotation/relaxation measurements on
single crystals of the spin-1/2 kagome antiferromagnet Herbertsmithite. We find
that the spins are more easily polarized when the field is perpendicular to the
kagome plane. We demonstrate that the difference in magnetization between the
different directions cannot be accounted for by Dzyaloshinksii-Moriya type
interactions alone, and that anisotropic axial interaction is present.Comment: 8 pages, 3 figures, accepted to JPCM special issue on geometrically
frustrated magnetis
The Magnetic Phase of Lithium Transition Metal Phosphates LiMPO4 (M=Mn, Co, Ni) Detected by μ+SR
AbstractThe magnetic properties of the olivine-type compounds LiMPO4 (M = Mn, Co, Ni) are probed using muon spin rotation/relaxation (μSR). These materials pose an appealing magnetic structure and a high -potential technological interest as cathode materials for future rechargeable Li-ion batteries. The LiMPO4 family of compounds consists of a corner-sharing MO6 octahedra of high-spin M2+ ions manifesting an antiferromagnetic ground state below TN ≈ 30K. Additionally, these compounds belong to a class of materials exhibiting properties between two-and three dimensional systems. A comparative study between the family members is presented
Static magnetic order in NaCoO detected by muon spin rotation and relaxation
The nature of the magnetic transition of the Na-rich thermoelectric
NaCoO at 22K was studied by positive muon-spin-rotation and
relaxation (SR) spectroscopy, using a polycrystalline sample in the
temperature range between 300 and 2.5 K. Zero field SR measurements
indicated the existence of a static internal magnetic field at temperatures
below 22 K (= ). The observed muon spin precession signal below
consisted of three components with different precession
frequencies, corresponding to three inequivalent muon sites in the
NaCoO lattice. The total volume fraction of the three components
was estimated as 21% at 2.5 K; thus, this magnetic transition was not
induced by impurities but is an intrinsic change in the magnetism of the
sample, although the sample was magnetically inhomogeneous otherwise. On the
other hand, a similar experiment on a NaCoO sample exhibited no
magnetic transition down to 2.5 K; which indicates that the average valence of
the Co ions is responsible for inducing the magnetic transition at 22 K.Comment: 5 pages, 4 figures, Phys. Rev. B 68 (2003) in pres