18 research outputs found
Strain Tuning Three-state Potts Nematicity in a Correlated Antiferromagnet
Electronic nematicity, a state in which rotational symmetry is spontaneously
broken, has become a familiar characteristic of many strongly correlated
materials. One widely studied example is the discovered Ising-nematicity and
its interplay with superconductivity in tetragonal iron pnictides. Since
nematic directors in crystalline solids are restricted by the underlying
crystal symmetry, recently identified quantum material systems with three-fold
rotational (C3) symmetry offer a new platform to investigate nematic order with
three-state Potts character. Here, we report reversible strain tuning of the
three-state Potts nematicity in a zigzag antiferromagnetic insulator, FePSe3.
Probing the nematicity via optical linear dichroism, we demonstrate either
2{\pi}/3 or {\pi}/2 rotation of nematic director by uniaxial strain. The nature
of the nematic phase transition can also be controlled such that it undergoes a
smooth crossover transition, a Potts nematic transition, or a Ising nematic
flop transition. The ability to tune the nematic order with in-situ strain
further enables the extraction of nematic susceptibility, which exhibits a
divergent behavior near the magnetic ordering temperature. Our work points to
an active control approach to manipulate and explore nematicity in three-state
Potts correlated materials.Comment: 20 pages, 4 figures, 6 additional figures. Initial submission on May
30t
Pseudogap behavior in charge density wave kagome material ScVSn revealed by magnetotransport measurements
Over the last few years, significant attention has been devoted to studying
the kagome materials AVSb (A = K, Rb, Cs) due to their unconventional
superconductivity and charge density wave (CDW) ordering. Recently
ScVSn was found to host a CDW below 90K, and, like
AVSb, it contains a kagome lattice comprised only of V ions. Here we
present a comprehensive magnetotransport study on ScVSn. We discovered
several anomalous transport phenomena above the CDW ordering temperature,
including insulating behavior in interlayer resistivity, a strongly
temperature-dependent Hall coefficient, and violation of Kohler's rule. All
these anomalies can be consistently explained by a progressive decrease in
carrier densities with decreasing temperature, suggesting the formation of a
pseudogap. Our findings suggest that high-temperature CDW fluctuations play a
significant role in determining the normal state electronic properties of
ScVSn
Chirality selective magnon-phonon hybridization and magnon-induced chiral phonons in a layered zigzag antiferromagnet
Two-dimensional (2D) magnetic systems possess versatile magnetic order and
can host tunable magnons carrying spin angular momenta. Recent advances show
angular momentum can also be carried by lattice vibrations in the form of
chiral phonons. However, the interplay between magnons and chiral phonons as
well as the details of chiral phonon formation in a magnetic system are yet to
be explored. Here, we report the observation of magnon-induced chiral phonons
and chirality selective magnon-phonon hybridization in a layered zigzag
antiferromagnet (AFM) FePSe. With a combination of magneto-infrared and
magneto-Raman spectroscopy, we observe chiral magnon polarons (chiMP), the new
hybridized quasiparticles, at zero magnetic field. The hybridization gap
reaches 0.25~meV and survives down to the quadrilayer limit. Via first
principle calculations, we uncover a coherent coupling between AFM magnons and
chiral phonons with parallel angular momenta, which arises from the underlying
phonon and space group symmetries. This coupling lifts the chiral phonon
degeneracy and gives rise to an unusual Raman circular polarization of the
chiMP branches. The observation of coherent chiral spin-lattice excitations at
zero magnetic field paves the way for angular momentum-based hybrid phononic
and magnonic devices
Absence of nematic instability in the kagome metal CsVSb
Ever since the discovery of the charge density wave (CDW) transition in the
kagome metal CsVSb, the nature of its symmetry breaking is under
intense debate. While evidence suggests that the rotational symmetry is already
broken at the CDW transition temperature (), an additional
electronic nematic instability well below was reported based on
the diverging elastoresistivity coefficient in the anisotropic channel
(). Verifying the existence of a nematic transition below is not only critical for establishing the correct description of the CDW
order parameter, but also important for understanding the low-temperature
superconductivity. Here, we report elastoresistivity measurements of
CsVSb using three different techniques probing both isotropic and
anisotropic symmetry channels. Contrary to previous reports, we find the
anisotropic elastoresistivity coefficient is
temperature-independent except for a step jump at . The absence of
nematic fluctuations is further substantiated by measurements of the
elastocaloric effect, which show no enhancement associated with nematic
susceptibility. On the other hand, the symmetric elastoresistivity coefficient
increases below , reaching a peak value of 90 at K. Our results strongly indicate that the phase transition at is
not nematic in nature and the previously reported diverging elastoresistivity
is due to the contamination from the channel