Fully gapped superconductivity in centrosymmetric and noncentrosymmetric Re-B compounds probed with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>μ</mml:mi><mml:mi mathvariant="normal">SR</mml:mi></mml:math>

S. Sharma, Arushi, Kapil Motla, J. Beare, M. Nugent, M. Pula, T. J. S. Munsie, A. D. Hillier, R. P. Singh, G. M. Luke

Abstract

We present a comprehensive study on superconducting properties of Re$_7$B$_3$ and Re$_3$B through specific heat, magnetic susceptibility, resistivity, and transverse and zero-field muon spin rotation/relaxation ($\mu$SR) experiments on polycrystalline samples. Re$_7$B$_3$ (T$_C$ = 3.2~K) is a non-centrosymmetric type-II ($\kappa$ $\approx$ 9.27) superconductor in the weak coupling ($\lambda_{e-ph}$ = 0.54) regime. On the other hand, Re$_3$B (T$_C$ = 5.19~K) is a centrosymmetric type-II ($\kappa$ $\approx$ 34.55) superconductor in the moderate coupling ($\lambda_{e-ph}$ = 0.64) regime. Our transverse-field $\mu$SR measurements show evidence for isotropically gapped BCS type superconductivity with normalized gap ($\Delta_0/k_BT_C$) values of 1.69 (Re$_7$B$_3$) and 1.75 (Re$_3$B).

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• Physical review. B./Physical review. B - View
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