0000000000331054
AUTHOR
Tom Lancaster
Brief encounter at the molecular level: what muons tell us about molecule-based magnets
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…
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
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.
Lattice-Site-Specific Spin Dynamics in Double PerovskiteSr2CoOsO6
Magnetic properties and spin dynamics have been studied for the structurally ordered double perovskite Sr2CoOsO6. Neutron diffraction, muon-spin relaxation, and ac-susceptibility measurements reveal two antiferromagnetic (AFM) phases on cooling from room temperature down to 2 K. In the first AFM phase, with transition temperature TN1=108 K, cobalt (3d7, S=3/2) and osmium (5d2, S=1) moments fluctuate dynamically, while their average effective moments undergo long-range order. In the second AFM phase below TN2=67 K, cobalt moments first become frozen and induce a noncollinear spin-canted AFM state, while dynamically fluctuating osmium moments are later frozen into a randomly canted state at…
Two hybrid organometallic-inorganic layered magnets from the series [ ZIIICp*2] [ MIIMIII(ox)3] studied with μ+SR
We present zero-field muon spin relaxation (ZF-μ + SR) measurements on two examples of a new series of hybrid organometallic-inorganic layered magnets, namely ferromagnetic [FeCp* 2 ][MnCr(ox) 3 ] and ferrimagnetic [CoCp* 2 ][FeFe(ox) 3 ] (where ox = oxalate and Cp* = pentame- thyl-cyclopentadienyl). Both materials show multi-component muon spin precession signals characteristic of quasistatic magnetic fields at several distinct muon sites. The temperature dependence of the precession frequencies allow critical exponents to be extracted. Possible muon sites are discussed on the basis of dipole field calculations.
Quantum Phases and Spin Liquid Properties of 1T-TaS2
Quantum materials exhibiting magnetic frustration are connected to diverse phenomena including high-Tc superconductivity, topological order and quantum spin liquids (QSLs). A QSL is a quantum phase (QP) related to a quantum-entangled fluid-like state of matter. Previous experiments on QSL candidate materials are usually interpreted in terms of a single QP, although theories indicate that many distinct QPs are closely competing in typical frustrated spin models. Here we report on combined temperature-dependent muon spin relaxation and specific heat measurements for the triangular-lattice QSL candidate material 1T-TaS2 that provide evidence for competing QPs. The measured properties are assig…