Muon spin rotation and relaxation in magnetic materials

Abstract

A review of the muon spin rotation and relaxation (µSR) studies on magnetic materials published from July 1993 is presented. It covers the investigation of magnetic phase diagrams, that of spin dynamics and the analysis of the magnetic properties of superconductors. We have chosen to focus on selected experimental works in these different topics. In addition, a list of published works is provided. Contents1. Introduction 2. µSR: muon spin rotation, relaxation 2.1. The transverse depolarization function 2.2. The longitudinal depolarization function 2.3. The magnetic field at the muon site 3. Magnetic phase diagrams 3.1. Magnetic ordering in organic compounds 3.2. Magnetic ordering in spin chains and ladders 3.3. Diamagnetic domains in beryllium 3.4. Localized and itinerant f electrons in heavy-fermion materials 4. Spin dynamics in magnets 4.1. Critical and low-temperature spin dynamics in ferromagnets 4.2. The correlation function in spin glasses 5. Probing the magnetic properties of superconductors 5.1. The symmetry of the superconducting order parameter in YBa 2 Cu 3 O 6.95 5.2. The vortex state in highly anisotropic high-T c superconductors 5.3. Anisotropy of the magnetic response in UPt 3 6. Summary and perspectives 7. List of works published from July 1993 Appendix A. The magnetic field at the muon site A.1. The magnetic field in the laboratory and crystal reference frames A.2. The Fourier components of the magnetic field A.3. The field distribution at the muon site Appendix B. Muon spin relaxation in a longitudinal field Appendix C. The longitudinal relaxation rate and correlation functions Appendix D. The µSR response function for hard superconductors

Structural and magnetic properties of the5d2double perovskitesSr2BReO6(Aczel1, Zhao2, Calder3 et al. 2016Phys. Rev. B233244View full textAdd to dashboardCite

“…At the highest temperatures measured β → 2, which is consistent with expectations that the dominant relaxation mechanism in this regime arises from static nuclear moments. With decreasing T , β → 1 and λ shows a small monotonic increase; this is precisely the behavior expected for a dilute, quasi-static electron spin system [32]. The LF-µSR spectra shown in Fig.…”

“…The null diffraction result for Sr 2 YReO 6 implies that the ordered Re moment is drastically-reduced as compared to its Ni counterparts or long-range order is absent down to 4 K. The former is possible due to increased covalency or enhanced spin-orbit cou- pling, and has been experimentally proven for Ba 2 CaOsO 6 [27], where an ordered moment of ∼ 0.2µ B was estimated from muon spin relaxation (µSR) measurements. The µSR technique [32] allows additional constraints to be placed on the possible magnetic ground state for Sr 2 YReO 6 . µSR is an extremely sensitive probe of magnetism and can readily differentiate between ordered, glassy, and dynamic ground states; ordered moments as small as 0.01 µ B can be easily detected.…”

“…We used the EMU and MuSR spectrometers in longitudinal geometry for investigating Sr 2 InReO 6 (closed cycle refrigerator, base T = 7.5 K) and Sr 2 YReO 6 (He-flow cryostat, base T = 1.4 K) respectively. The time-evolution of the spin polarization of the muon ensemble was measured via the asymmetry function, A(t) [32].…”

Spin-liquid ground state in the frustratedJ1−J2zigzag chain systemBaTb2O4Aczel1, Li2, Garlea3 et al. 2015Phys. Rev. B141110View full textAdd to dashboardCite

“…A single exponential muon spin relaxation rate from the sample is also observed at all temperatures. These findings are indicative of large, rapidly-fluctuating internal magnetic fields, as expected for a paramagnet 38,46 , and they are in good agreement with the decoupling scheme observed in the LF scan at 0.095 K.…”

“…For example, diffuse scattering was observed in diffraction measurements of the pyrochlore systems Tb 2 Mo 2 O 7 37 and Tb 2 Ti 2 O 7 38 , but the molybdate has been characterized as a spin glass 44 while the titanate is a quantum spin ice candidate 45 . Muon spin relaxation (µSR) measurements 46 proved to be instrumental in searching for the evidence of spin freezing needed to differentiate between spin glass and more exotic dynamic ground states in these pyrochlore systems 38,47 . Therefore, to better understand the magnetic ground state of BaTb 2 O 4 , µSR was performed at the EMU (10-300 K) and MuSR (0.095-4 K) spectrometers in longitudinal field (LF) geometry at the ISIS Pulsed Neutron and Muon Source.…”