Effects of Disorder on Magnetic Penetration Depth near Quantum Critical Point in Single Crystals of (Ca_xSr_1−x)₃Rh₄Sn₁₃ Superconductor

In (Ca_xSr_1−x)₃Rh₄Sn₁₃ superconductivity (SC) coexists with the charge-density-wave (CDW) with the suggested quantum critical point (QCP) at x_c = 0.9. In addition to stoichiometry and pressure, the quantum phase transition in this system has also been tuned to by a controlled nonmagnetic point-like disorder induced by 2.5 MeV electron irradiation [1]. To get further insight into the putative QCP, we studied London (λ_L), and Campbell (λ_c), magnetic field penetration depths in pristine and electron-irradiated samples. We examine the prediction of a T-linear low-temperature variation of λ_L(T) near QCP [2], analyze the absolute value, λ_L(x,0) [3,4], and probe vortex properties via λ_c(T,H), which gives direct access to the true critical current density and shape of the pinning potential. In conclusion, we compare the predictions and observations near magnetic (in iron pnictides [3,4]) and structural (this work) QCP.

[1] Elizabeth H. Krenkel and Makariy A. Tanatar and Romain Grasset and Marcin Kończykowski and Shuzhang Chen and Cedomir Petrovic and Alex Levchenko and Ruslan Prozorov, arXiv:2406.16157 (2024)

[2] Jaglul Hasan, Maxim Dzero, Maxim Khodas and Alex Levchenko, Phys. Rev. B 105, 054510 (2022)

[3] K. Hashimoto, Kyuil Cho, T. Shibauchi, S. Kasahara, Y. Mizukami, R. Katsumata, Y. Tsuruhara, T. Terashima, H. Ikeda, M. A. Tanatar, H. Kitano, N. Salovich, R.W. Giannetta, P. Walmsley, A. Carrington, R. Prozorov, Y. Matsuda, Science 336, 1554(2012)

[4] Kamal R Joshi, NM Nusran, Makariy A Tanatar, Kyuil Cho, Sergey L Bud’ko, Paul C Canfield, Rafael M Fernandes, Alex Levchenko, Ruslan Prozorov, New J. Phys. 22, 053037 (2020)