MuFinder: A program to determine and analyse muon stopping sites

by Dr Benjamin Huddart (Department of Physics, Durham University)

Thursday 9 Jun 2022, 13:30 → 14:30 Europe/Zurich

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Over the past decade there has been significant progress in calculating muon stopping sites using first-principles methods such as density functional theory (DFT). However, such calculations are still only carried out by a relatively small number of research groups and are not yet a routine part of analysing a muon-spin spectroscopy (µSR) experiment. Here I introduce MuFinder [1], a program that facilitates the process of calculating muon sites by allowing these calculations to be run through a graphical user interface, with the aim of making this procedure more accessible to users who are not necessarily experts in electronic structure methods.  I will demonstrate how muon site calculations can be carried out using MuFinder and then illustrate how they can enhance the interpretation of µSR experiments using examples from my research. First, I show how knowledge of the muon sites helps us to understand how the muon provides sensitivity to the unpaired spins in layers of the candidate quantum spin liquid material 1T-TaS2. In the second example, I show how DFT calculations of muon-stopping states provide evidence that the spontaneous local magnetic fields detected using muons in superconductors with time-reversal symmetry breaking (TRSB) are intrinsic to the TRSB superconducting state and not the result of a muon-induced perturbation [3].

1. B. M. Huddart et al. arXiv:2110.07341 [cond-mat.str-el].
2. S. Mañas-Valero et al., npj Quantum Mater. 6, 69 (2021).
3. B. M. Huddart et al. Phys. Rev. Lett. 127, 237002 (2021).

MuFinder_talk.pdf