Search results for "Muon spin spectroscopy"
showing 10 items of 21 documents
Quantum critical point in the itinerant ferromagnet Ni$_{1-x}$Rh$_x$
2020
We report a chemical substitution-induced ferromagnetic quantum critical point in polycrystalline Ni$_{1-x}$Rh$_x$ alloys. Through magnetization and muon spin relaxation measurements, we show that the ferromagnetic ordering temperature is suppressed continuously to zero at $x_{crit} = 0.375$ while the magnetic volume fraction remains 100% up to $x_{crit}$, pointing to a second order transition. Non-Fermi liquid behavior is observed close to $x_{crit}$, where the electronic specific heat $C_{el}/T$ diverges logarithmically, while immediately above $x_{crit}$ the volume thermal expansion coefficient $\alpha_{V}/T$ and the Gr\"uneisen ratio $\Gamma = \alpha_{V}/C_{el}$ both diverge logarithmic…
The muon magnetic moment
1981
Muon mass and muon magnetic moment are not calculabIe within the theory of Quantum Eiectrodynamics; they rather define the reference acaie in which masses and energies should be determined when muons are used to test QED or to search for anomalous muon coupiings which couid provide the "raison d'@tre" for the muon. Oniy the anomaious part of the muon magnetic moment experimentaily determined with remarkable precision I), can be oaIculated 2~" Theory and experiment agree preciseiy once corrections being appiied for hadronic and weak processes which poiiute the immaculated fieid of QED at high momentum transfers. Muon mass and muon magnetic moment are, in particular, needed for the interpreta…
Magnetic order and local field distribution in the hybrid magnets [FeCp*(2)][MnCr(ox)(3)] and [CoCp*(2)][FeFe(ox)(3)]: a muon spin relaxation study
2016
Zero-field muon spin relaxation (μ+SR) measurements on materials from the series [ZIIICp*2][M IIMIII(ox)3] show precession signals at several frequencies, characteristic of quasistatic magnetic fields at up to three distinct muon sites.
Brief encounter at the molecular level: what muons tell us about molecule-based magnets
2005
Abstract Spin-polarized muons can be implanted in various molecular magnetic materials in order to measure static and dynamic magnetic field distributions at a local level. The positively-charged muon is an unstable, radioactive particle which has spin–1/2, a lifetime of 2.2 μ S , about one-ninth of the proton mass and a magnetic moment of approximately 1/200 μ B . Both pulsed and continuous beams of muons can be produced with almost 100% spin polarization and significant intensity at various accelerator facilities. The subsequent decay of the muon into a positron allows the extraction of the muon-spin autocorrelation function which can be related to the magnetic field distribution inside a…
Positive Muons as Local Probes in Paramagnetic Rare Earth Systems
1982
In recent years a new research method has been developed in solid state physics which is based on the asymmetry of muon decay1. A positive muon at rest decays after a mean lifetime of 2.2 μsec into a positron and two neutrinos, the positron being emitted preferentially in the direction of the muon spin. Hence if spin polarized muons are implanted in a solid, the time evolution of the muon spin polarization can be determined by a measurement of the angular distribution of the positrons. In an external magnetic field transverse to the initial spin direction of the muon one can study the muon spin precession frequency, which is determined by the actual field at the muon, and τ2-relaxation effe…
Thermal disorder driven magnetic phases in van der Waals magnet CrI3
2020
Abstract Magnetic phase transitions often occur spontaneously at specific critical temperatures and are instrumental to understand the origin of long-range spin order in condensed matter systems. The presence of more than one critical temperature (Tc) has been observed in several compounds where the coexistence of competing magnetic orders highlights the importance of phase separation driven by different factors such as pressure, temperature and chemical composition. However, it is unknown whether recently discovered two-dimensional (2D) van der Walls (vdW) magnetic materials show such intriguing phenomena that can result in rich phase diagrams with novel magnetic features to be explored. H…
Neutron optics P-violation effects near p-wave resonance
1999
Abstract The observations of large enhancement of parity-violation at p-wave compound resonance encourage prompt active discussion of TRI test in neutron optics. One of the most attractive objects for investigation is the p-wave resonance of 139 La at energy 0.734 eV for which the strongest P-odd effect of spin dichroism has been observed. A new technique of neutron spin analysis based on optically pumped 3 He spin filter has been applied successfully to measure the complementary effect of P-odd spin rotation near the same p-wave resonance of 139 La . The results obtained are consistent with theory predictions.
Magnetic Ordering and Spin Dynamics of Ba1-xEuxSi Phases
2011
We have investigated the magnetic ordering and spin dynamics of the solid solution series Ba1–xEuxSi with 0 < x ≤ 1 applying X-ray diffraction, electric conductivity measurements, Mossbauer spectroscopy, muon spin depolarization, and neutron diffraction. Our results suggest a spin glass-like behavior of Ba1–xEuxSi for concentrations close to x = 0.3 exist. Different spin ordering phenomena are found, which are dependent on the relative europium concentrations.
Muon spin relaxation studies of iron(II) spin crossover complexes
2008
A series of model iron(II) spin crossover complexes have been investigated by temperature dependent muon spin relaxation (mu SR) techniques at ISIS, UK. The thermally induced spin crossover in these materials could be monitored by following the initial asymmetry parameter, a(0), in zero-field. We established that the behavior of a(0) correlates well with the shape of the spin crossover curve derived from magnetic susceptibility measurements, whether hysteretic, smooth, or abrupt. In addition, the longitudinal field dependence of a(0) not only provides information on the nature of the muonic species but also on their interactions and respective localization in the crystal lattice. Useful ins…
Heavy ion induced columnar defects: a sensitive probe for the 2D/3D behaviour of vortex matter in high-temperature superconductors
1998
Abstract Heavy ion irradiation is used to create columnar defects in high-temperature superconductors (HTS). The heavy ion induced defects are not only very well controlled in shape and density, but also in the direction of the tracks with respect to the crystallographic c-axis. Pinning of the flux lines as a function of magnetic field orientation then becomes dependent on vortex dimensionality. The two-dimensional (2D)/three-dimensional (3D) behaviour of flux lines was investigated in the highly anisotropic Bi-based superconducting oxide. Results obtained from transport current measurements with epitaxial films, measurements with small single crystals in flux transformer geometry and muon …