31 research outputs found
Refined test of AdS4/CFT3 correspondence for N=2,3 theories
We investigate the superconformal indices for the Chern-Simons-matter
theories proposed for M2-branes probing the cones over N^{010}/Z_k, Q^{111},
M^{32} with N=2,3 supersymmetries and compare them with the corresponding dual
gravity indices. For N^{010}, we find perfect agreements. In addition, for
N^{010}/Z_k, we also find an agreement with the gravity index including the
contributions from two types of D6-branes wrapping RP^3. For Q^{111}, we find
that the model obtained by adding fundamental flavors to the N=6 theory has the
right structure to be the correct model. For M^{32}, we find the matching with
the gravity index modulo contributions from peculiar saddle points.Comment: 35 pages, 1 figure, v2: added references and comment
Symmetry-Protected Solitons and Bulk-Boundary Correspondence in Generalized Jackiw-Rebbi Models
We investigate the roles of symmetry and bulk-boundary correspondence in
characterizing topological edge states in generalized Jackiw-Rebbi (JR) models.
We show that time-reversal (), charge-conjugation (), parity (), and
discrete internal field rotation () symmetries protect and characterize
the various types of edge states such as chiral and nonchiral solitons via
bulk-boundary correspondence in the presence of the multiple vacua. As two
representative models, we consider the JR model composed of a single fermion
field having a complex mass and the generalized JR model with two massless but
interacting fermion fields. The JR model shows nonchiral solitons with the
rotation symmetry, whereas it shows chiral solitons with the broken
rotation symmetry. In the generalized JR model, only nonchiral solitons can
emerge with only rotation symmetry, whereas both chiral and nonchiral
solitons can exist with enhanced rotation symmetry. Moreover, we find
that the nonchiral solitons have symmetries while the chiral solitons do
not, which can be explained by the symmetry-invariant lines connecting
degenerate vacua. Finally, we find the symmetry correspondence between
multiply-degenerate global vacua and solitons such that , ,
symmetries of a soliton inherit from global minima that are connected by the
soliton, which provides a novel tool for the characterization of topological
solitons
Topological Domain-Wall States Hosting Quantized Polarization and Majorana Zero Modes Without Bulk Boundary Correspondence
Bulk-boundary correspondence is a concept for topological insulators and
superconductors that determines the existence of topological boundary states
within the tenfold classification table. Contrary to this belief, we
demonstrate that topological domain-wall states can emerge in all forbidden 1D
classes in the classification table using representative generalized
Su-Schrieffer-Heeger and Kitaev models, which manifests as quantized electric
dipole moments and Majorana zero modes, respectively. We first show that a
zero-energy domain-wall state can possess a quantized polarization, even if the
polarization of individual domains is not inherently quantized. A quantized
Berry phase difference between the domains confirms the non-trivial nature of
the domain-wall states, implying a general-bulk-boundary principle, further
confirmed by the tight-binding, topological field, and low-energy effective
theories. Our methodology is then extended to a superconducting system,
resulting in Majorana zero modes on the domain wall of a generalized Kitaev
model. Finally, we suggest potential systems where our results may be realized,
spanning from condensed matter to optical
Nanoscale manipulation of the Mott insulating state coupled to charge order in 1T-TaS2
The controllability over strongly correlated electronic states promises unique electronic devices. A recent example is an optically induced ultrafast switching device based on the transition between the correlated Mott insulating state and a metallic state of a transition metal dichalcogenide 1T-TaS2. However, the electronic switching has been challenging and the nature of the transition has been veiled. Here we demonstrate the nanoscale electronic manipulation of the Mott state of 1T-TaS2. The voltage pulse from a scanning tunnelling microscope switches the insulating phase locally into a metallic phase with irregularly textured domain walls in the charge density wave order inherent to this Mott state. The metallic state is revealed as a correlated phase, which is induced by the moderate reduction of electron correlation due to the charge density wave decoherence.131321sciescopu
Duality between N=5 and N=6 Chern-Simons matter theory
We provide evidences for the duality between Chern-Simons matter theory and theory for a suitable by working out the
superconformal index, which shows perfect matching. For theories,
we show that supersymmetry is enhanced to by explicitly
constructing monopole operators filling in -currents. Finally we
work out the large index of and show that
it exactly matches with the gravity index on , which
further provides additional evidence for the duality between the
and theory for Comment: 15 pages; references adde
SIM(2)-invariant Modifications of Electrodynamic Theory
In the Cohen-Glashow Very Special Relativity we exhibit possible
modifications to the Maxwell theory and to the quantum electrodynamics
Lagrangian in some generality, and discuss characteristic features depending on
the modifications. Modified gauge transformations in SIM(2)-invariant theories
are introduced, and in these theories gauge fields with two polarization states
can have nonzero mass. Also considered are SIM(2)-covariant modifications to
the Proca-type field equations for a massive spin-1 particle
Unconventional Anomalous Hall Effect from Antiferromagnetic Domain Walls of Nd\u3csub\u3e2\u3c/sub\u3eIr\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e7\u3c/sub\u3e Thin Films
Ferroic domain walls (DWs) create different symmetries and ordered states compared with those in single-domain bulk materials. In particular, the DWs of an antiferromagnet with noncoplanar spin structure have a distinct symmetry that cannot be realized in those of their ferromagnet counterparts. In this paper, we show that an unconventional anomalous Hall effect (AHE) can arise from the DWs of a noncoplanar antiferromagnet, Nd2Ir2O7. Bulk Nd2Ir2O7 has a cubic symmetry; thus, its Hall signal should be zero without an applied magnetic field. The DWs generated in this material break the twofold rotational symmetry, which allows for finite anomalous Hall conductivity. A strong f−d exchange interaction between the Nd and Ir magnetic moments significantly influences antiferromagnetic (AFM) domain switching. Our epitaxial Nd2Ir2O7 thin film showed a large enhancement of the AHE signal when the AFM domains switched, indicating that the AHE is mainly due to DWs. Our paper highlights the symmetry-broken interface of AFM materials as a means of exploring topological effects and their relevant applications