Metal-Insulator and Magnetic **Phase** Diagram of Ca$_2$RuO$_4$ from
Auxiliary Field Quantum Monte Carlo and Dynamical Mean Field Theory

**phase**

**transitions**easily tuned by temperature, pressure, epitaxy, and nonlinear drive. In this work, we combine results from two complementary state of the art many-body methods, Auxiliary Field Quantum Monte Carlo and Dynamical Mean Field Theory, to determine the low-temperature

**phase**diagram of Ca$_2$RuO$_4$. Both methods predict a low temperature, pressure-driven metal-insulator

**transition**accompanied by a ferromagnetic-antiferromagnetic

**transition**. The properties of the ferromagnetic state vary non-monotonically with pressure and are dominated by the ruthenium $d_{xy}$ orbital, while the properties of the antiferromagnetic state are dominated by the $d_{xz}$ and $d_{yz}$ orbitals. Differences of detail in the predictions of the two methods are analyzed. This work is theoretically important as it presents the first application of the Auxiliary Field Quantum Monte Carlo method to an orbitally-degenerate system with both Mott and Hunds physics, and provides an important comparison of the Dynamical Mean Field and Auxiliary Field Quantum Monte Carlo methods.

4/10 relevant

arXiv

Six-loop $\varepsilon$ expansion study of three-dimensional $O(n)\times O(m)$ spin models

**phase**

**transitions**into chiral

**phases**should be first-order.

4/10 relevant

arXiv

Gravitational Waves from **Phase** **Transition** in Minimal SUSY $U(1)_{B-L}$
Model

**phase**

**transition**occurs at nucleation temperature of $O(100)$-$O(1000)$~TeV, it can generate stochastic gravitational waves in $O(10)$-$O(100)$ Hz range if $\beta_{\rm n}/H_{\rm n}=1000$, which can be detected by ground-based detectors. Meanwhile, supersymmetry (SUSY) may play a crucial role in the dynamics of such high-scale $U(1)$ gauge symmetry breaking, because SUSY breaking scale is expected to be at TeV to solve the hierarchy problem. In this paper, we study the

**phase**

**transition**of $U(1)$ gauge symmetry breaking in a SUSY model in the SUSY limit. We consider a particular example, the minimal SUSY $U(1)_{B-L}$ model. We derive the finite temperature effective potential of the model in the SUSY limit, study a $U(1)_{B-L}$-breaking

**phase**transition, and estimate gravitational waves generated from it.

9/10 relevant

arXiv

Confinement/deconfinement **phase** **transition** and dual Meissner effect in
SU(3) Yang-Mills theory

**phase**

**transition**is associated with the appearance/disappearance of the induced magnetic--monopole current, respectively. Expand abstract.

**phase**

**transition**at finite temperature of the SU(3) Yang-Mills(YM) theory on the lattice from a viewpoint of the dual superconductor picture based on the novel reformulation of the YM theory. In particular, we compare the conventional Abelian dual superconductor picture with the non-Abelian dual superconductor picture proposed in our previous works as the mechanism of quark confinement in the SU(3) YM theory. For the SU(3) YM theory, the reformulation allows two possible options called maximal and minimal. The maximal option corresponds to the manifestly gauge-invariant extension of the Abelian projection scheme, while the minimal option is really new to give the non-Abelian dual superconductor picture. Keeping these differences in mind, we present the numerical evidences that the confinement/deconfinement

**phase**

**transition**is caused by appearance/disappearance of the dual Meissner effects. First, we measure the Polyakov loop average at various temperatures to determine the critical temperature separating the low-temperature confined

**phase**and the high-temperature deconfined

**phase**. Second, we measure the static quark-antiquark potential. Third, we measure the chromoelectric and chromomagnetic flux created by a pair of quark and antiquark at temperatures below and above the critical temperature. We observe no more squeezing of the chromoelectric flux tube above the critical temperature. Finally, we measure the associated magnetic--monopole current induced around the chromo-flux tube and observe that the confinement/deconfinement

**phase**

**transition**is associated with the appearance/disappearance of the induced magnetic--monopole current, respectively. We confirm that these results are also obtained by the restricted field alone in both options, indicating the restricted field dominance in quark confinement at finite temperature.

8/10 relevant

arXiv

Optically Driven Magnetic **Phase** **Transition** of Monolayer RuCl3

**phase**

**transition**is driven by a combined effect of doping-induced lattice strain and itinerant ferromagnetism. Expand abstract.

**phase**to a stable ferromagnetic

**phase**. Specifically, a moderate electron-hole pair density (on the order of 10^13 cm-2) can significantly stabilize the ferromagnetic

**phase**by 10 meV/f.u. in comparison to the zigzag phase, so that the predicted ferromagnetism can be driven by optical pumping experiments. Analysis shows that this magnetic

**phase**

**transition**is driven by a combined effect of doping-induced lattice strain and itinerant ferromagnetism. According to the Ising-model calculation, we find that the Curie temperature of the ferromagnetic

**phase**can be increased significantly by raising carrier or electron-hole pair density. This enhanced opto-magnetic effect opens new opportunities to manipulate two-dimensional magnetism through non-contact, optical approaches.

8/10 relevant

arXiv

**Phase** Diagrams of Single Layer Two-Dimensional **Transition** Metal
Dichalcogenides: Landau Theory

**phase**

**transitions**. Expand abstract.

**transition**metal dichalcogenides (TMDs), such as MoS2, ReS2, WSe2, and MoTe2 have now become the focus of intensive fundamental and applied researches due to their intriguing and tunable physical properties. These materials exhibit a broad range of structural

**phases**that can be induced via elastic strain, chemical doping, and electrostatic field effect. These

**transitions**in turn can open and close the band gap of SL-TMDs, leading to metal-insulator transitions, and lead to emergence of more complex quantum phenomena. These considerations necessitate detailed understanding of the mesoscopic mechanisms of these structural

**phase**

**transitions**. Here we develop the Landau-type thermodynamic description of SL-TMDs on example of SL-(MoS2)1-x-(ReS2)x system and analyze the free energy surfaces,

**phase**diagrams, and order parameter behavior. Our results predict the existence of multiple structural

**phases**with 2-, 6- and 12-fold degenerated energy minima for in-plane and out of plane order parameters. This analysis suggests that out-of-plane ferroelectricity can exist in many of these phases, with the switchable polarization being proportional to the out-of-plane order parameter. We further predict that the domain walls in SL-(MoS2)1-x-(ReS2)x should become conductive above a certain strain threshold.

7/10 relevant

arXiv

Role of spin mixing conductance in determining thermal spin pumping near
the ferromagnetic **phase** **transition** in EuO_{1-x} and La2NiMnO6

4/10 relevant

arXiv

Relativistic hybrid stars with sequential first-order **phase** **transitions**
and heavy-baryon envelopes

**phase**

**transitions**from hadronic to quark phase(s). These quantities are computed for three types of hadronic envelopes: purely nuclear, hyperonic, and $\Delta$-resonance--hyperon admixed matter. We consider either a single first-order

**phase**

**transition**to a quark

**phase**with a maximally stiff equation of state (EoS) or two sequential first-order

**phase**

**transitions**mimicking a

**transition**from hadronic to a quark matter

**phase**followed by a second

**phase**

**transition**to another quark

**phase**. We explore the parameter space which produces low mass twin and triplet configurations where equal mass stars have substantially different radii and tidal deformabilities. We demonstrate that while for purely hadronic stiff EoS the obtained maximum mass is inconsistent with the upper limit on this quantity placed by GW170817, the inclusion of the hyperonic and $\Delta$-resonance degrees of freedom, as well as the deconfinement

**phase**

**transition**at sufficiently low density, produce configuration of stars consistent with this limit. The obtained hybrid star configurations are in the mass range relevant for the interpretation of the GW170817 event. We compare our results for the tidal deformability with the limits inferred from GW170817 showing that the onset of non-nucleonic phases, such as $\Delta$-resonance--hyperon admixed

**phase**or/and the quark phase(s) is favored by this data if the nuclear EoS is stiff. Also, we show that low-mass twins and especially triplets proliferate the number of combinations of possible types of star that can undergo a merger event, the maximal number being six in the case of triplets. The prospects for uncovering the first-order

**phase**transition(s) to and in quark matter via measurements of tidal deformabilities in merger events are discussed.

10/10 relevant

arXiv

Fermion-induced quantum critical point in Dirac semimetals: a sign-problem-free quantum Monte Carlo study

**phase**

**transition**should be first order when cubic terms of order parameters are allowed in its effective Ginzburg-Landau free energy. Recently, it was shown by renormalization group (RG) analysis that continuous

**transition**can happen at putatively first-order $Z_3$

**transitions**in 2D Dirac semimetals and such non-Landau

**phase**

**transitions**were dubbed "fermion-induced quantum critical points" (FIQCP) [Li et al., Nature Communications 8, 314 (2017)]. The RG analysis, controlled by the 1/$N$ expansion with $N$ the number of flavors of four-component Dirac fermions, shows that FIQCP occurs for $N\geq N_c$. Previous QMC simulations of a microscopic model of SU($N$) fermions on the honeycomb lattice showed that FIQCP occurs at the

**transition**between Dirac semimetals and Kekule-VBS for $N\geq 2$. However, precise value of the lower bound $N_c$ has not been established. Especially, the case of $N=1$ has not been explored by studying microscopic models so far. Here, by introducing a generalized SU($N$) fermion model with $N=1$ (namely spinless fermions on the honeycomb lattice), we perform large-scale sign-problem-free Majorana quantum Monte Carlo simulations and find convincing evidence of FIQCP for $N=1$. Consequently, our results suggest that FIQCP can occur in 2D Dirac semimetals for all positive integers $N\geq 1$.

7/10 relevant

arXiv

Non-Hermitian topological **phase** **transitions** for quantum spin Hall
insulators

**phase**

**transitions**to/from quantum spin Hall (QSH) insulators driven by non-Hermiticity. We show that a trivial to QSH insulator

**phase**

**transition**can be induced by solely varying non-Hermitian terms, and there exists exceptional edge arcs in QSH

**phases**. We establish two topological invariants for characterizing the non-Hermitian

**phase**transitions: i) with time-reversal symmetry, the biorthogonal $\mathbb{Z}_2$ invariant based on non-Hermitian Wilson loops, and ii) without time-reversal symmetry, a biorthogonal spin Chern number through biorthogonal decompositions of the Bloch bundle of the occupied bands. These topological invariants can be applied to a wide class of non-Hermitian topological

**phases**beyond Chern classes, and provides a powerful tool for exploring novel non-Hermitian topological matter and their device applications.

10/10 relevant

arXiv