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arXiv · 2204.02852

Muon spin rotation and relaxation study on Nb$_{1-y}$Fe$_{2+y}$

J. Willwater·D. Eppers·T. Kimmel·E. Sadrollahi·F. J. Litterst·F. M. Grosche·C. Baines·S. Süllow
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Abstract

We present a detailed study of the magnetic properties of weakly ferromagnetic/quantum critical Nb$_{1-y}$Fe$_{2+y}$ using muon spin rotation and relaxation ($\mu$SR). By means of an angular dependent study of the muon spin rotation signal in applied magnetic fields on a single crystal in the paramagnetic state we establish the muon stopping site in the crystallographic lattice of NbFe$_2$. With this knowledge we develop models to describe the muon spin rotation and relaxation signals in the weakly ferromagnetic, spin density wave and quantum critical phases of Nb$_{1-y}$Fe$_{2+y}$ and fit the corresponding experimental data. In particular, we quantify the $\mu$SR response for quantum critical behavior in Nb$_{1.0117}$Fe$_{1.9883}$ and extract the influence of residual weak structural disorder. From our analysis, Nb$_{1-y}$Fe$_{2+y}$ emerges to be uniquely suited to study quantum criticality close to weak itinerant ferromagnetic order.

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J. Willwater, D. Eppers, T. Kimmel, E. Sadrollahi, F. J. Litterst, F. M. Grosche, C. Baines, S. Süllow. 2022-04-06. Muon spin rotation and relaxation study on Nb$_{1-y}$Fe$_{2+y}$. https://doi.org/10.1103/physrevb.106.134408

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