Who
Sudarshan Sharma (McMaster University)
Abstract
Unconventional superconductors are the class of superconductors that do not follow the properties of conventional BCS superconductors. Search for new unconventional superconductors and understanding their properties is one of the important research avenues for the last few decades as it can lead to new insights, which can be crucial for developing high-temperature superconductors and new technologies. Many of the unconventional superconductors discovered to date belong to non-centrosymmetric superconductors. Non-centrosymmetric superconductors, where the crystal structure breaks the inversion symmetry, antisymmetric spin-orbital coupling (ASOC) is allowed by symmetry. This can seriously affect the superconducting state if this ASOC is large. Some of the consequences of this could be the presence of a mixture of spin-singlet and triplet cooper pairs, line, or point nodes in the superconducting gap [1]. I will present the superconducting properties of Re 3 B, Re 7 B 3 , TaReSi, and TaRuSi [2-3] to discuss the role of crystal structure and ASOC in determining unconventional superconducting properties.
In the remaining time, I will discuss the magnetic properties of geometrically frustrated breathing pyrochlore magnets CuAlCr 4 S 8 [4]. A magnetic pyrochlore lattice comprises a three-dimensional array of corners sharing tetrahedra. A type of this structure with different sizes of the tetrahedra is known as breathing pyrochlore. Cr-based pyrochlores tend to show strong magnetoelastic coupling. This unique combination of bond alternation and magnetoelastic coupling leads to various exotic properties like negative thermal expansion [5], classical spin nematic transition [6], etc.
[1] M Smidman et al. Rep. Prog. Phys. 80 036501 (2017)
[2] S Sharma et al. 2021 Phys Rev. B. 103, 104507 (2021)
[3] S Sharma et al. 2023 arXiv:2209.09852v1 (2023)
[4] S Sharma et al. 2022 Phys. Rev. B 106, 024407 (2022)
[5] G. Pokharel et al. Phys. Rev. Lett. 125, 167201 (2020)
[6] R. Wawrzynczak et al., Phys. Rev. Lett. 119, 087201 (2017)
In the remaining time, I will discuss the magnetic properties of geometrically frustrated breathing pyrochlore magnets CuAlCr 4 S 8 [4]. A magnetic pyrochlore lattice comprises a three-dimensional array of corners sharing tetrahedra. A type of this structure with different sizes of the tetrahedra is known as breathing pyrochlore. Cr-based pyrochlores tend to show strong magnetoelastic coupling. This unique combination of bond alternation and magnetoelastic coupling leads to various exotic properties like negative thermal expansion [5], classical spin nematic transition [6], etc.
[1] M Smidman et al. Rep. Prog. Phys. 80 036501 (2017)
[2] S Sharma et al. 2021 Phys Rev. B. 103, 104507 (2021)
[3] S Sharma et al. 2023 arXiv:2209.09852v1 (2023)
[4] S Sharma et al. 2022 Phys. Rev. B 106, 024407 (2022)
[5] G. Pokharel et al. Phys. Rev. Lett. 125, 167201 (2020)
[6] R. Wawrzynczak et al., Phys. Rev. Lett. 119, 087201 (2017)