713 research outputs found
Effect of Applied Orthorhombic Lattice Distortion on the Antiferromagnetic Phase of CeAuSb
We study the response of the antiferromagnetism of CeAuSb to orthorhombic
lattice distortion applied through in-plane uniaxial pressure. The response to
pressure applied along a lattice direction shows a
first-order transition at zero pressure, which shows that the magnetic order
lifts the symmetry of the unstressed lattice. Sufficient
pressure appears to rotate the principal axes of the
order from to . At low pressure, the transition at is weakly first-order, however it
becomes continuous above a threshold pressure. We discuss
the possibility that this behavior is driven by order parameter fluctuations,
with the restoration of a continuous transition a result of reducing the
point-group symmetry of the lattice.Comment: 6 pages, 7 figure
Nematic Fermi Fluids in Condensed Matter Physics
Correlated electron fluids can exhibit a startling array of complex phases,
among which one of the more surprising is the electron nematic, a
translationally invariant metallic phase with a spontaneously generated spatial
anisotropy. Classical nematics generally occur in liquids of rod-like
molecules; given that electrons are point-like, the initial theoretical
motivation for contemplating electron nematics came from thinking of the
electron fluid as a quantum melted electron crystal, rather than a strongly
interacting descendent of a Fermi gas. That such phases exist in nature was
established by dramatic transport experiments in ultra-clean quantum Hall
systems in 1999 and in Sr3Ru2O7 in a strong magnetic field in 2007.
In this paper, we briefly review the theoretical considerations governing
nematic order, summarize the quantum Hall and Sr3Ru2O7 experiments that
unambiguously establish the existence of this phase, and survey some of the
current evidence for such a phase in the cuprate and Fe-based high temperature
superconductors.Comment: 30 pages, 7 figures (some in color); to appear in Annual Reviews of
Condensed Matter Physics. Edited version
Piezoelectric-based apparatus for strain tuning
We report the design and construction of piezoelectric-based apparatus for
applying continuously tuneable compressive and tensile strains to test samples.
It can be used across a wide temperature range, including cryogenic
temperatures. The achievable strain is large, so far up to 0.23% at cryogenic
temperatures. The apparatus is compact and compatible with a wide variety of
experimental probes. In addition, we present a method for mounting
high-aspect-ratio samples in order to achieve high strain homogeneity.Comment: 8 pages, 8 figure
Even odder after twenty-three years : the superconducting order parameter puzzle of Sr2RuO4
Funding: Max Planck Society.In this short review, we aim to provide a topical update on the status of efforts to understand the superconductivity of Sr2RuO4. We concentrate on the quest to identify a superconducting order parameter symmetry that is compatible with all the major pieces of experimental knowledge of the material, and highlight some major discrepancies that have become even clearer in recent years. As the pun in the title suggests, we have tried to start the discussion from scratch, making no assumptions even about fundamental issues such as the parity of the superconducting state. We conclude that no consensus is currently achievable in Sr2RuO4, and that the reasons for this go to the heart of how well some of the key probes of unconventional superconductivity are really understood. This is therefore a puzzle that merits continued in-depth study.Publisher PDFPeer reviewe
Effect of uniaxial stress on the magnetic phases of CeAuSb
We present results of measurements of resistivity of \CAS{} under the
combination of -axis magnetic field and in-plane uniaxial stress. In
unstressed \CAS{} there are two magnetic phases. The low-field A phase is a
single-component spin-density wave (SDW), with , and the high-field B phase consists of microscopically coexisting
and spin-density waves. Pressure along
a lattice direction is a transverse field to both of
these phases, and so initially has little effect, however eventually induces
new low- and high-field phases in which the principal axes of the SDW
components appear to have rotated to the directions.
Under this strong compression, the field evolution of the
resistivity is much smoother than at zero strain: In zero strain, there is a
strong first-order transition, while under strong it
becomes much broader. We hypothesize that this is a consequence of the uniaxial
stress lifting the degeneracy between the (100) and (010) directions.Comment: 8 pages, 7 figure
Hydrodynamic electron flow and Hall viscosity
The authors acknowledge support from the Emergent Phenomena in Quantum Systems initiative of the Gordon and Betty Moore Foundation (T. S.) and NSF DMR-1507141 and a Simons Investigatorship (J. E. M.). We also acknowledge the support of the Max Planck Society and the UK Engineering and Physical Sciences Research Council under Grant No. EP/I032487/1.In metallic samples of small enough size and sufficiently strong momentum-conserving scattering, the viscosity of the electron gas can become the dominant process governing transport. In this regime, momentum is a long-lived quantity whose evolution is described by an emergent hydrodynamical theory. Furthermore, breaking time-reversal symmetry leads to the appearance of an odd component to the viscosity called the Hall viscosity, which has attracted considerable attention recently due to its quantized nature in gapped systems but still eludes experimental confirmation. Based on microscopic calculations, we discuss how to measure the effects of both the even and odd components of the viscosity using hydrodynamic electronic transport in mesoscopic samples under applied magnetic fields.PostprintPeer reviewe
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