Theoretical studies for identifying horizontal line nodes via angle-resolved density of states measurements ---Application to Sr${}_2$RuO${}_4$---

Abstract

On the basis of the microscopic quasi-classical Eilenberger theory, we analyze the recent angle-resolved specific heat experiment carried out at low temperature for Sr${}_2$RuO${}_4$ to identify the superconducting gap symmetry, comprising either horizontal or vertical line nodes relative to the tetragonal crystal symmetry. Several characteristics, in particular, the landscape of the in-plane oscillation amplitude $A_4(B,T)$ with a definite sign for almost the entire $B$-$T$ plane are best explained by the horizontal line node symmetry, especially when the multiband effect and Pauli paramagnetic effect are taken into account. The present analysis of $A_4(B,T)$ with definite sign points to the presence of an anomalous field region at a lower temperature in the experimental data, whose origin is investigated. Our theory demonstrates the application and uniqueness of the field-rotating thermodynamic measurements in uncovering the precise gap structure for target materials.

15 pages, 28 figures

References in corpus (15)

• High Resolution Polar Kerr Effect Measurements of Sr2RuO4: Evidence for Broken Time Reversal Symmetry in the Superconducting State
• Observation of half-height magnetization steps in Sr2RuO4
• First-Order Superconducting Transition of Sr2RuO4
• The Fermi surface of Sr2RuO4: spin-orbit and anisotropic Coulomb interaction effects
• Orientational field-dependence of low-lying excitations in mixed state of unconventional superconductors
• Sharp magnetization jump at the first-order superconducting transition in Sr2RuO4
• Little-Parks oscillations with half-quantum fluxoid features in Sr2RuO4 micro rings
• Specific-heat evidence of the first-order superconducting transition in Sr2RuO4
• Vortex State and Field-Angle Resolved Specific Heat Oscillation for H // ab in d-Wave Superconductors
• Analytical Formulation of the Local Density of States around a Vortex Core in Unconventional Superconductors
• Pauli-paramagnetic effects on mixed state properties in a strongly anisotropic superconductor ---Application to Sr_2_RuO_4_---
• Ubiquitous V-shape density of states in mixed state of clean limit type II superconductors; STM experiment and theory
• Anisotropy and multiband superconductivity in Sr2RuO4
• Searching for zeroes: unconventional superconductors in a magnetic field
• Eilenberger theory and London theory for transverse components of flux line lattice form factors in uniaxial superconductors