Theoretical studies on off-axis phase diagrams and Knight shifts in UTe${}_2$ -- Tetra-critical point, d-vector rotation, and multiple phases

Abstract

Inspired by recent remarkable sets of experiments on UTe${}_2$: discoveries of the fourth horizontal internal transition line running toward a tetra-critical point (TCP) at $H$=15T, the off-axis high field phases, and abnormally large Knight shift (KS) drop below $T_{\mathrm{c}}$ for $H$$\parallel$$a$-magnetic easy axis, we advance further our theoretical work on the field ($H$)-temperature ($T$) phase diagram for $H$$\parallel$$b$-magnetic hard axis which contains a positive sloped $H_{c2}$ departing from TCP. A nonunitary spin-triplet pairing with three components explains these experimental facts simultaneously and consistently by assuming that the underlying normal electron system with a narrow bandwidth characteristic to the Kondo temperature $\sim$60K unsurprisingly breaks the particle-hole symmetry. This causes a special invariant term in Ginzburg-Landau (GL) free energy functional which couples directly with the 5f magnetic system, giving rise to the $T_{\mathrm{c}}$ splitting and ultimately to the positive sloped $H_{c2}$ and the horizontal internal transition line connected to TCP. The large KS drop can be understood in terms of this GL invariance whose coefficient is negative and leads to a diamagnetic response where the Cooper pair spin is antiparallel to the applied field direction. The present scenario also accounts for the observed d-vector rotation phenomena and off-axis phase diagrams with extremely high $H_{c2}$$\gtrsim$70T found at angles in between the $b$ and $c$-axes and between the $bc$ plane and $a$-axis, making UTe${}_2$ a fertile playground for a topological superconductor.

23 pages, 21 figures

References in corpus (53)

• Theory of Intertwined Orders in High Temperature Superconductors
• Microscopic evidence for a chiral superconducting order parameter in the heavy fermion superconductor UTe2
• The Order Parameter for the Superconducting Phases of UPt${}_3$
• Unconventional Superconductivity in Heavy Fermion UTe2
• Review of U-based Ferromagnetic Superconductors: Comparison between UGe2, URhGe, and UCoGe
• Unconventional Superconductivity in UTe2
• Detection of a Pair Density Wave State in UTe${}_2$
• Metamagnetic Transition in Heavy Fermion Superconductor UTe2
• Point Node Gap Structure of Spin-Triplet Superconductor UTe2
• Multiple Superconducting Phases and Unusual Enhancement of the Upper Critical Field in UTe2
• Superconducting Properties of Heavy Fermion UTe${}_2$ Revealed by ${}^{125}$Te-Nuclear Magnetic Resonance
• Incommensurate Spin Fluctuations in the Spin-triplet Superconductor Candidate UTe${}_2$
• 125Te-NMR Study on a Single Crystal of Heavy Fermion Superconductor UTe2
• First Observation of de Haas-van Alphen Effect and Fermi Surfaces in Unconventional Superconductor UTe2
• Low-dimensional antiferromagnetic fluctuations in the heavy-fermion paramagnetic ladder UTe${}_2$
• Large Reduction in the $a$-axis Knight Shift on UTe${}_2$ with $T_{\mathrm{c}}$ = 2.1 K
• Superconducting order parameter in UTe${}_2$ determined by Knight shift measurement
• Orientational field-dependence of low-lying excitations in mixed state of unconventional superconductors
• Anisotropic response of spin susceptibility in the superconducting state of UTe${}_2$ probed with ${}^{125}$Te-NMR measurement
• Chiral superconductivity in UTe2 probed by anisotropic low-energy excitations
• Orientation of point nodes and nonunitary triplet pairing tuned by the easy-axis magnetization in UTe2
• Anisotropy of the Upper Critical Field in the Heavy-Fermion Superconductor UTe2 under Pressure
• Tuning magnetic confinement of spin-triplet superconductivity
• Interplay between magnetism and superconductivity in UTe2
• A review of UTe${}_2$ at high magnetic fields
• Magnetic Properties under Pressure in Novel Spin-Triplet Superconductor UTe2
• Fully gapped pairing state in spin-triplet superconductor UTe${}_2$
• Change of superconducting character in UTe2induced by magnetic field
• Field-Induced Superconductivity near the Superconducting Critical Pressure in UTe2
• Field Induced Multiple Superconducting Phases in UTe2 along Hard Magnetic Axis
• Symmetry of magnetic correlations in spin-triplet superconductor UTe2
• Field-Orientation Dependence of Low-Energy Quasiparticle Excitations in the Heavy-Electron Superconductor UBe13
• Absence of Spontaneous Magnetic Fields Due to Time-Reversal Symmetry Breaking in Bulk Superconducting UTe2
• Inhomogeneous Superconducting State Probed by ${}^{125}$Te NMR on UTe$_2
• Dimensionality driven enhancement of ferromagnetic superconductivity in URhGe
• Violation of the Pauli-Clogston limit in a heavy Fermion superconductor CeRh${}_2$As${}_2$ --Duality of itinerant and localized 4f electrons--
• Slow Electronic Dynamics in the Paramagnetic State of UTe${}_2$
• Quasiparticle Excitations and Evidence for Superconducting Double Transitions in Monocrystalline U0.97Th0.03Be13
• Superconducting-Spin Reorientation in Spin-Triplet Multiple Superconducting Phases of UTe2
• Theory of spin-polarized superconductors -- an analogue of superfluid ${}^3$He A-phase
• Enhancement and Discontinuity of Effective Mass through the First-Order Metamagnetic Transition in UTe${}_2$
• Expansion of the high field-boosted superconductivity in UTe2 under pressure
• Field-induced compensation of magnetic exchange as the possible origin of reentrant superconductivity in UTe${}_2$
• Non-unitary triplet superconductivity tuned by field-controlled magnetization --URhGe, UCoGe and UTe${}_2$--
• Anomalous Anisotropy of the Lower Critical Field and Meissner Effect in UTe2
• Possible Coexistence of Antiferromagnetic and Ferromagnetic Spin Fluctuations in the Spin-triplet Superconductor UTe2 Revealed by 125Te NMR under Pressure
• Longitudinal spin fluctuations driving field-reinforced superconductivity in UTe${}_2$
• Theory of Pairing Assisted Spin Polarization in Spin-Triplet Equal Spin Pairing: Origin of Extra Magnetization in Sr_2RuO_4 in Superconducting State
• Thermodynamic transitions and topology of spin-triplet superconductivity: Application to UTe${}_2$
• Notes on multiple superconducting phases in UTe${}_2$ ---Third transition---
• Anisotropic Enhancement of Lower Critical Field in Ultraclean Crystals of Spin-Triplet Superconductor UTe2
• Theory of the low- and high-field superconducting phases of UTe${}_2$
• Violation of the orbital depairing limit in a non-unitary state --on the high field phase in the heavy Fermion superconductor UTe${}_2$--

Cited by in corpus (2)

• Observation of Persistent Zero Modes and Superconducting Vortex Doublets in UTe${}_2$
• Nodal Superconductivity of UTe${}_2$ Probed by Field-Angle-Resolved Specific Heat on a Crystal with $T_{\mathrm{c}}=2.1$ K