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Previous studies [1,2] reported on superconductivity (SC) observed for alloy systems with the general formula Mo$_{1-x}$Re$_x$. In order to probe this behaviour further, three samples Mo$_{73.5}$Re$_{26.5}$, Mo$_{67.1}$Re$_{32.9}$, and Mo$_{79.5}$Re$_{20.5}$ were prepared and characterized. Pure elements, 99.99 % in purity, of Mo and Re were used to synthesize the three samples utilizing the arc-melting technique. Analysis of x-ray diffraction results show that these alloys exhibit both body-centred cubic (BCC) and the A15 phases. The A15 phase, with a $\beta$-W crystal structure, is typically observed in intermetallic compounds of the form Y$_3$Z, where Y is a transition metal, and Z is any element and is associated with superconducting behaviour [3]. The four-probe method was used for resistivity as a function of temperature, $\rho(T)$, measurements. All the samples showed normal metallic behaviour on cooling down from 300 K to the temperature associated with the onset of SC, $T_{sc}$, where a clear anomaly in the form of a step in the $\rho(T)$ curve is observed. As the applied magnetic fields are increased, the $T_{sc}$ values shift to lower temperatures. Alternating current heat capacity measurements as a function of temperature, $C_p(T)$, were performed. Clear transitions, in the form of humps, are observed in the $C_p(T)$ curves of the Mo$_{67.1}$Re$_{32.9}$ and Mo$_{79.5}$Re$_{20.5}$ samples, corresponding to $T_{sc}$ values of $(9.53 \pm 0.02)$ K and $(9.98 \pm 0.05)$ K, respectively.
References
[1] Sundar, S., Chandra, L.S., Chattopadhyay, M.K., Pandey, S.K., Venkateshwarlu, D., Rawat, R., Ganesan, V. and Roy, S.B., 2015. Strong electron-phonon coupling and multiband effects in the superconducting $\beta$-phase Mo$_{1−x}$Re$_x$ alloys. New Journal of Physics, 17(5), p.053003.
[2] Shang, T., Gawryluk, D.J., Verezhak, J.A., Pomjakushina, E., Shi, M., Medarde, M., Mesot, J. and Shiroka, T., 2019. Structure and superconductivity in the binary Re$_{1−x}$Mo$_x$ alloys. Physical Review Materials, 3(2), p.024801.
[3] Chourasia, S., Kamra, L.J., Bobkova, I.V. and Kamra, A., 2023. Generation of spin-triplet Cooper pairs via a canted antiferromagnet. Physical Review B, 108(6), p.064515.
| Apply for student award at which level: | MSc |
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