Anomalous Anisotropy of the Lower Critical Field and Meissner Effect in UTe2

Abstract

We report on low temperature susceptibility and magnetization measurements made on single crystals of the recently discovered heavy-fermion superconductor UTe${}_2$ and compare the results with the two ambient pressure ferromagnetic superconductors URhGe and UCoGe. Hysteresis curves in the superconducting phase show a familiar diamond shape superimposed on a large paramagnetic background. The Meissner state was measured by zero field cooling in small fields of a few Oe as well as ac susceptibility measurements in small fields and resulted in 100\% shielding, with a sharp transition. However the field cooling Meissner-Ochsenfeld effect (expulsion of flux) was negligible in fields greater than just a few Oe, but becomes nearly 30\% of the perfect diamagnetic signal when the field was reduced to 0.01~Oe. The critical current due to flux pinning was studied by ac susceptibility techniques. Over the range in fields and temperature of this study, no signature of a ferromagnetic transition could be discerned. The lower critical field $H_{c1}$ has been measured along the three crystalographic axes, and surprisingly, the anisotropy of $H_{c1}$ contradicts that of the upper critical field. We discuss this discrepancy and show that it may provide additional support for a magnetic field-dependent pairing mediated by ferromagnetic fluctuations in UTe${}_2$.

5 pages, 4 figures, supplemental material included, to appear in Phys. Rev B (Letter)

References in corpus (14)

• Superconductivity on the border of weak itinerant ferromagnetism in UCoGe
• Unconventional Superconductivity in Heavy Fermion UTe2
• Review of U-based Ferromagnetic Superconductors: Comparison between UGe2, URhGe, and UCoGe
• Metamagnetic Transition in Heavy Fermion Superconductor UTe2
• Evidence for a pressure-induced antiferromagnetic quantum critical point in intermediate valence UTe2
• 125Te-NMR Study on a Single Crystal of Heavy Fermion Superconductor UTe2
• Magnetic-Field-Induced Phenomena in the Paramagnetic Superconductor UTe${}_2$
• 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
• Thermodynamic Investigation of Metamagnetism in Pulsed High Magnetic Fields on Heavy Fermion Superconductor UTe${}_2$
• Absence of Meissner State and Robust Ferromagnetism in the Superconducting State of UCoGe: Possible Evidence of Spontaneous Vortex State
• Quantum Criticality in the Ferromagnetic Superconductor UCoGe under Pressure and Magnetic Field
• Wing structure in the phase diagram of the Ising Ferromagnet URhGe close to its tricritical point investigated by angle-resolved magnetization measurements
• Weyl Superconductivity in UTe2

Cited by in corpus (20)

• Unconventional Superconductivity in UTe2
• Evidence for a pressure-induced antiferromagnetic quantum critical point in intermediate valence UTe2
• Superconducting order parameter in UTe${}_2$ determined by Knight shift measurement
• Field-induced tuning of the pairing state in a superconductor
• A review of UTe${}_2$ at high magnetic fields
• Interplay between magnetism and superconductivity in UTe2
• The fate of time-reversal symmetry breaking in UTe2
• Magnetic Properties under Pressure in Novel Spin-Triplet Superconductor UTe2
• Anapole superconductivity from $\mathcal{P}\mathcal{T}$-symmetric mixed-parity interband pairing
• Microscopic imaging homogeneous and single phase superfluid density in UTe${}_2$
• Enhancement and Discontinuity of Effective Mass through the First-Order Metamagnetic Transition in UTe${}_2$
• Magnetic reshuffling and feedback on superconductivity in UTe2 under pressure
• Magnetovolume Effect on the First-Order Metamagnetic Transition in UTe${}_2$
• Clear Reduction in Spin Susceptibility and Superconducting Spin Rotation for $H\parallel a$ in the Early-Stage Sample of Spin-Triplet Superconductor UTe${}_2$
• Anisotropic Enhancement of Lower Critical Field in Ultraclean Crystals of Spin-Triplet Superconductor UTe2
• Incommensurate antiferromagnetism in UTe2 under pressure
• Theoretical studies on off-axis phase diagrams and Knight shifts in UTe${}_2$ -- Tetra-critical point, d-vector rotation, and multiple phases
• Dramatic elastic response at the critical end point in UTe${}_2$
• Observation of vortex stripes in UTe${}_2$
• Metamagnetism in the high-pressure tetragonal phase of UTe${}_2$