Title:	Effect of Uniaxial strain on electron-phonon coupling and super-conducting properties of ZrB2
DNr:	SNIC 2021/23-474
Project Type:	SNIC Small Storage
Principal Investigator:	Per Eklund <per.eklund@liu.se>
Affiliation:	Linköpings universitet
Duration:	2021-08-17 – 2021-11-01
Classification:	10304
Keywords:

Abstract

The discovery of high superconducting transition temperature (~39 K) in magnesium di-borides (MgB2) [1], motivated researchers for the study of superconductivity in other transition metal borides such as ZrB2, ScB2, TiB2, NbB2, MoB2, WB2 etc [2,3,4]. Recent studies reveal that ZrB2, a non-superconducting material, shows superconductivity upon V or Nb doping. The incorporation of 4% of V or Nb transforms ZrB2 into a multiband superconductor with a transition temperature of 5.5 K and 8.1 K, respectively[5]. Upon incorporation of V and Nb, the lattice parameters of ZrB2 decreases, and compressive strain is introduced in the parent lattice. However, little is known about the impact of the doping induced strain on the superconductivity in ZrB2. In this proposed project, we aim to investigate the effect of the uniaxial compressive strain on the electronic structure, phonon dispersion and electron-phonon coupling in strained ZrB2. Finally, by solving the anisotropic Migdal-Eliashberg equation we will estimate superconducting transition temperature upon doping in ZrB2. A theoretical mechanism and correlation between superconductivity and strain are expected to be derived within this project. Our recent computed results have proven that the superconductivity in doped ZrB2 is of unconventional origin (under review[6]). At this stage, we are attempting to provide a more reliable explanation for electron-phonon coupling in doped ZrB2 by employing a supercell approach. The minimum number of atoms for this work will be around 24. For “a large” number of atoms, especially computing electron-phonon coupling matrix elements is computationally expensive. This also requires relatively larger disk space to store the computed data. With currently allocated disk space (500 GiB) we can not store all metadata that is required for analysis and needed another 500 GiB of storage space for the project. With this proposal, we are requesting you to kindly grant us extra storage of 500 GiB. Reference 1. J. Akimitsu et al., Nature, 410, 6364(2001) 2. G.L. Bhalla et al., J. of Appl. Phys. 105, 07E313 (2009) 3. A. N. Alexandrova et al., J. Mater. Chem. C 7, 10700 (2019) 4. R J Cava et al., Supercond. Sci. Technol. 31, 115005 (2018) 5. J. Mesot et al., Phys. Rev. B 95, 094505 (2017) 6. S Nayak, Under Review(2021)