Muons and magnets

Abstract:

We describe how the presence of magnetic breakdown affects the appearance of angle-dependent magnetoresistance oscillations in an organic metal. The model takes account of all the contributions from quasiparticles undergoing both magnetic breakdown and Bragg reflection at each junction and allows extremely efficient simulation of data which can be compared with experimental results on κ-(BEDT-TTF)2Cu(NCS)2. © 2010 Elsevier B.V. All rights reserved.

Abstract:

We address the cause of the unusual muon spin-relaxation (μ+ SR) results on molecular nanomagnets (MNMs). Through measurements on protonated and deuterated samples of the MNMs Cr7 Mn (S=1) and Cr8 (S=0), we show that the muon spin for S≠0 MNMs is relaxed via dynamic fluctuations of the electronic spins. A freezing out of dynamic processes occurs on cooling and at low temperatures the muon spins are relaxed by the electronic spins which themselves are dephased by incoherent nuclear-field fluctuations. We observe a transition to a state of static magnetic order of the MNM electronic spins in Cr7Mn below 2 K. © 2010 The American Physical Society.

Abstract:

We report results of muon-spin-rotation measurements performed on the ferromagnetic semiconductor EuO, which is one of the best approximations to a localized ferromagnet. We argue that implanted muons are sensitive to the internal field primarily through a combination of hyperfine and Lorentz fields. The temperature dependences of the internal field and the relaxation rate have been measured and are compared with previous theoretical predictions. © 2010 The American Physical Society.