Magnetic memory and spontaneous vortices in a van der Waals superconductor

Abstract

Doped Mott insulators exhibit some of the most intriguing quantum phases of matter, including quantum spin-liquids, unconventional superconductors, and non-Fermi liquid metals. Such phases often arise when itinerant electrons are close to a Mott insulating state, and thus experience strong spatial correlations. Proximity between different layers of van der Waals heterostructures naturally realizes a platform for experimentally studying the relationship between localized, correlated electrons and itinerant electrons. Here, we explore this relationship by studying the magnetic landscape of 4Hb-TaS2, which realizes an alternate stack of a candidate spin liquid and a superconductor. We report on a spontaneous vortex phase whose vortex density can be trained in the normal state. We show that time reversal symmetry is broken above Tc, indicating the presence of a magnetic phase independent of the superconductor. Strikingly, this phase does not generate detectable magnetic signals. We use scanning superconducting quantum interference device (SQUID) microscopy to show that it is incompatible with ferromagnetic ordering. The discovery of this new form of hidden magnetism illustrates how combining superconductivity with a strongly correlated system can lead to new, unexpected physics.

References in corpus (12)

• Magnetic order in the pseudogap phase of high-$T_C$ superconductors
• Polar Kerr Effect Measurements of YBa2Cu3O6+x: Evidence for Broken Symmetry Near the Pseudogap Temperature
• Observation of broken time-reversal symmetry in the heavy fermion superconductor UPt${}_3$
• Imaging spinon density modulations in a 2D quantum spin liquid
• Visualization of Topological Boundary Modes Manifesting Topological Nodal-Point Superconductivity
• Quartic metal: Spontaneous breaking of time-reversal symmetry due to four-fermion correlations in Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$
• Graphene/$\alpha$-RuCl${}_3$: An Emergent 2D Plasmonic Interface
• Gapless excitations in the ground state of 1T-TaS${}_2$
• Tunneling spectroscopy of quantum spin liquids
• Doping the chiral spin liquid -- topological superconductor or chiral metal?
• Evidence of Spontaneous Vortex Ground State in An Iron-Based Ferromagnetic Superconductor
• Artificial heavy fermions in a van der Waals heterostructure

Cited by in corpus (9)

• Chiral to Nematic Crossover in the Superconducting State of 4Hb-TaS${}_2$
• Striped electronic phases in an incommensurately modulated van der Waals superlattice
• Weak-Coupling Theory of Pair Density-Wave Instabilities in Transition Metal Dichalcogenides
• Evidence of a two-component order parameter in 4Hb-TaS2 in the Little-Parks effect
• Nematic Ising superconductivity with hidden magnetism in few-layer 6R-TaS2
• Kondo enabled transmutation between spinons and superconducting vortices: origin of magnetic memory in 4Hb-$\mathrm{Ta}{\mathrm{S}}_2$
• Is spontaneous vortex generation in superconducting 4Hb-TaS${}_2$ from vison-vortex nucleation with ${\mathbb{Z}}_2$ topological order?
• $T-$linear resistivity from magneto-elastic scattering: application to PdCrO${}_2$
• Local magnetic moments due to loop currents in metals