Rotation of Triangular Vortex Lattice in the Two-Band Superconductor MgB2
To identify the contributions of the multiband nature and the anisotropy of a microscopic electronic structure to a macroscopic vortex lattice morphology, we develop a method based on the Eilenberger theory near $H_{\text{c2}}$ combined with the first-principles band calculation to estimate the stab...
Saved in:
| Published in: | Journal of the Physical Society of Japan Vol. 82; no. 6; pp. 063708 - 063708-4 |
|---|---|
| Main Authors: | , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
The Physical Society of Japan
15-06-2013
|
| Online Access: | Get full text |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | To identify the contributions of the multiband nature and the anisotropy of a microscopic electronic structure to a macroscopic vortex lattice morphology, we develop a method based on the Eilenberger theory near $H_{\text{c2}}$ combined with the first-principles band calculation to estimate the stable vortex lattice configuration. For a typical two-band superconductor MgB 2 , successive transitions of vortex lattice orientation that have been observed recently by small angle neutron scattering [Das et al.: Phys. Rev. Lett. 108 (2012) 167001] are explained by the characteristic field-dependence of two-band superconductivity and the competition of sixfold anisotropy between the $\sigma$- and $\pi$-bands. The reentrant transition at low temperature reflects the Fermi velocity anisotropy of the $\sigma$-band. |
|---|---|
| Bibliography: | (Color online) (a) Schematic phase diagram of vortex lattice morphology as a function of $H$ and $T$, obtained by the SANS experiment. The phase boundary near $H_{\text{c2}}$ is extrapolated. Triangular lattices in the right panel show the orientation $\phi$ of each-phase. (b) The $T$ dependence of $\phi$ is schematically presented along $H_{\text{c2}}$. (Color online) (a) Fermi surfaces of MgB 2 obtained in our calcu lation. The two cylinders in the center are the $\sigma$-band's Fermi surface, and the outside rings are the $\pi$-band's Fermi surfaces. The color on the surface indicates the orientation $\varphi_{\mathbf{v}_{i}}$ (mod 30°) of the Fermi velocity. (b) $\varphi_{v}$-resolved Fermi surface DOS $D_{\sigma}(\varphi_{v})$ for the $\sigma$-band. (c) $D_{\pi}(\varphi_{v})$ for the $\pi$-band. In (b) and (c), we plot lines of $(D_{m}(\varphi_{v})\cos\varphi_{v},D_{m}(\varphi_{v})\sin\varphi_{v})$ for $0\leq\varphi_{v}\leq 360$° ($m=\sigma,\pi$), so that the distances from the center to the lines indicate $D_{m}(\varphi_{v})$. (Color online) (a) $\mathcal{F}'(\phi)/\mathcal{F}'(\phi=0)$ as a function of $\phi$ at $T/T_{\text{c}}=0.908$, 0.909, 0.911, 0.912, and 0.913, showing transition $\text{I}\rightarrow\text{L}\rightarrow\text{F}$, for (i) $V_{\sigma,\pi}=0.15V_{\sigma,\sigma}$, $V_{\pi,\pi}=0.32V_{\sigma,\sigma}$. The intervals of data points are 1° along each line. Arrows indicate the minimum of each line. (b) Stable orientation $\phi$ of triangular vortex lattice as a function of $T/T_{\text{c}}$ along $H_{\text{c2}}$ line. In addition to case (i), we also show lines for (ii) $V_{\sigma,\pi}=V_{\sigma,\sigma}/3$, $V_{\pi,\pi}=0$, (iii) $V_{\sigma,\pi}=V_{\sigma,\sigma}/2$, $V_{\pi,\pi}=0$, and (iv) $V_{\sigma,\pi}=V_{\sigma,\sigma}/3$, $V_{\pi,\pi}=V_{\sigma,\sigma}/2$. (c) The high-$T$ range of the transition $\text{I}\rightarrow\text{L}\rightarrow\text{F}$ of (i) is focused on. (Color online) Stable orientation $\phi$ as a function of $T/T_{\text{c}}$ along $H_{\text{c2}}$ line when only the $\sigma$-band is superconducting ($V_{\sigma,\pi}=V_{\pi,\pi}=0$) and when only the $\pi$-band is superconducting ($V_{\sigma,\pi}=V_{\sigma,\sigma}=0$). |
| ISSN: | 0031-9015 1347-4073 |
| DOI: | 10.7566/JPSJ.82.063708 |