Quartic metal: Spontaneous breaking of time-reversal symmetry due to four-fermion correlations in Ba$_{1-x}$K$_x$Fe$_2$As$_2$

• URL: http://arxiv.org/abs/2103.17190v2
• Date: Mon, 5 Jul 2021 16:31:06 GMT
• Title: Quartic metal: Spontaneous breaking of time-reversal symmetry due to four-fermion correlations in Ba$_{1-x}$K$_x$Fe$_2$As$_2$
• Authors: Vadim Grinenko, Daniel Weston, Federico Caglieris, Christoph Wuttke, Christian Hess, Tino Gottschall, Ilaria Maccari, Denis Gorbunov, Sergei Zherlitsyn, Jochen Wosnitza, Andreas Rydh, Kunihiro Kihou, Chul-Ho Lee, Rajib Sarkar, Shanu Dengre, Julien Garaud, Aliaksei Charnukha, Ruben H\"uhne, Kornelius Nielsch, Bernd B\"uchner, Hans-Henning Klauss, and Egor Babaev
• Abstract summary: Superconducting states are a spontaneously broken symmetry corresponding to long-range coherence of fermion pairs. We show that the formation of fermionic bound states leads to spontaneous breaking of time-reversal symmetry above the superconducting transition temperature.
• Score: 3.076082310544129
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Discoveries of ordered quantum states of matter are of great fundamental interest, and often lead to unique applications. The most well known example -- superconductivity -- is caused by the formation and condensation of pairs of electrons. A key property of superconductors is diamagnetism: magnetic fields are screened by dissipationless currents. Fundamentally, what distinguishes superconducting states from normal states is a spontaneously broken symmetry corresponding to long-range coherence of fermion pairs. Here we report a set of experimental observations in hole doped Ba$_{1-x}$K$_x$Fe$_2$As$_2$ which are not consistent with conventional superconducting behavior. Our specific-heat measurements indicate the formation of fermionic bound states when the temperature is lowered from the normal state. However, for $x \sim 0.8$, instead of the standard for superconductors, zero resistance and diamagnetic screening, for a range of temperatures, we observe the opposite effect: the generation of self-induced magnetic fields measured by spontaneous Nernst effect and muon spin rotation experiments. The finite resistance and the lack of any detectable diamagnetic screening in this state exclude the spontaneously broken symmetry associated with superconducting two-fermion correlations. Instead, combined evidence from transport and thermodynamic measurements indicates that the formation of fermionic bound states leads to spontaneous breaking of time-reversal symmetry above the superconducting transition temperature. These results demonstrate the existence of a broken-time-reversal-symmetry bosonic metal state. In the framework of a multiband theory, such a state is characterized by quartic correlations: the long-range order exists only for {\it pairs} of fermion pairs.

Related papers

• Unconventional high-temperature excitonic insulators in two-dimensional topological materials [0.0]
  Bound electron-hole pairs in semiconductors known as excitons can form a coherent state at low temperatures. The resulting phase is known as the excitonic insulator and has superfluid properties. We study the excitonic insulator in a pair of recently proposed two-dimensional candidate materials with nontrivial band topology.
  arXiv  Detail & Related papers  (2025-01-30T19:00:06Z)
• Exploiting the presence of chiral spin states in molecular nanomagnets [47.41699406259656]
  In a three-spin-center system, antiferromagnetic exchange interactions give rise to two ground-state doublets. We explore the presence of spin-chirality in Lanthanide complexes that feature two magnetic centers.
  arXiv  Detail & Related papers  (2025-01-21T08:23:12Z)
• Probing the magnetic origin of the pseudogap using a Fermi-Hubbard quantum simulator [30.29758729899544]
  In strongly correlated materials, interacting electrons are entangled and form collective quantum states. Superconductivity emerges at low doping out of an unusual pseudogap'' metallic state above the critical temperature. We use a quantum gas microscope Fermi-Hubbard simulator to explore a wide range of doping levels and temperatures.
  arXiv  Detail & Related papers  (2024-12-23T18:58:01Z)
• Superluminal Propagation of Composite Collective Modes in Superconductor-Ferromagnet Heterostructures [0.0]
  We show that the spectrum of composite collective modes, $omega(k)$, has a qualitatively different form in the case of $H_demH_an$ and of $H_dem>H_an$. For moderate or weak anisotropy in ferromagnet the group velocity of collective modes demonstrates inflection point where the group velocity become infinite and is superluminal.
  arXiv  Detail & Related papers  (2024-07-07T18:01:17Z)
• Formation of robust bound states of interacting microwave photons [148.37607455646454]
  One of the hallmarks of interacting systems is the formation of multi-particle bound states. We develop a high fidelity parameterizable fSim gate that implements the periodic quantum circuit of the spin-1/2 XXZ model. By placing microwave photons in adjacent qubit sites, we study the propagation of these excitations and observe their bound nature for up to 5 photons.
  arXiv  Detail & Related papers  (2022-06-10T17:52:29Z)
• Thermal self-oscillations in monolayer graphene coupled to a superconducting microwave cavity [58.720142291102135]
  We observe thermal self-oscillations in a monolayer graphene flake coupled to superconducting resonator. The experimental observations fit well with theoretical model based on thermal instability. The modelling of the oscillation sidebands provides a method to evaluate electron phonon coupling in disordered graphene sample at low energies.
  arXiv  Detail & Related papers  (2022-05-27T15:38:41Z)
• In-Gap Band Formation in a Periodically Driven Charge Density Wave Insulator [68.8204255655161]
  Periodically driven quantum many-body systems host unconventional behavior not realized at equilibrium. We investigate such a setup for strongly interacting spinless fermions on a chain, which at zero temperature and strong interactions form a charge density wave insulator.
  arXiv  Detail & Related papers  (2022-05-19T13:28:47Z)
• Metastable spin-phase diagrams in antiferromagnetic Bose-Einstein condensates [0.0]
  We study theoretically the metastable spin-phase diagram of a spin-1 antiferromagnetic Bose-Einstein condensate at zero and finite temperatures. Results are consistent with recent experiments and allow us to explain qualitatively the different types of observed quench dynamics.
  arXiv  Detail & Related papers  (2021-09-05T03:47:59Z)
• Dissipation-induced symmetry breaking: Emphanitic transitions in lead- and tin-containing chalcogenides and halide perovskites [0.0]
  emphanisis is the name given to the observed displacement of the lead or the tin ions from their cubic symmetry ground state to a locally distorted phase at high temperature. We propose a quantum tunneling-based model for emphanisis where decoherence is responsible for the local symmetry breaking with increasing temperature.
  arXiv  Detail & Related papers  (2020-12-10T06:50:43Z)
• Collective spontaneous emission of two entangled atoms near an oscillating mirror [50.591267188664666]
  We consider the cooperative spontaneous emission of a system of two identical atoms, interacting with the electromagnetic field in the vacuum state. Using time-dependent theory, we investigate the spectrum of the radiation emitted by the two-atom system. We show that it is modulated in time, and that the presence of the oscillating mirror can enhance or inhibit the decay rate.
  arXiv  Detail & Related papers  (2020-10-07T06:48:20Z)
• Probing eigenstate thermalization in quantum simulators via fluctuation-dissipation relations [77.34726150561087]
  The eigenstate thermalization hypothesis (ETH) offers a universal mechanism for the approach to equilibrium of closed quantum many-body systems. Here, we propose a theory-independent route to probe the full ETH in quantum simulators by observing the emergence of fluctuation-dissipation relations. Our work presents a theory-independent way to characterize thermalization in quantum simulators and paves the way to quantum simulate condensed matter pump-probe experiments.
  arXiv  Detail & Related papers  (2020-07-20T18:00:02Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.