scholarly journals Symmetry breaking and (pseudo)spin polarization in Veselago lenses for massless Dirac fermions

2017 ◽  
Vol 95 (11) ◽  
Author(s):  
K. J. A. Reijnders ◽  
M. I. Katsnelson
Keyword(s):  
Symmetry Breaking ◽  
Spin Polarization ◽  
Dirac Fermions

scholarly journals B5N5 monolayer: a room-temperature light element antiferromagnetic insulator

2020 ◽  
Vol 2 (10) ◽  
pp. 4421-4426
Author(s):  
Dong Zhang ◽  
Qihua Xiong ◽  
Kai Chang
Keyword(s):  
Symmetry Breaking ◽  
Fermi Surface ◽  
Spontaneous Symmetry Breaking ◽  
Spin Polarization ◽  
Room Temperature ◽  
Light Element ◽  
Spin Filter ◽  
Flat Bands

In atomically-thick B5N5 monolayer, antiferromagnetism arises from spontaneous symmetry breaking due to flat bands in the vicinity of the Fermi surface. An electric-controllable prototype spin filter with nearly 100% spin polarization is proposed based on B5N5 monolayers.

scholarly journals Helical symmetry breaking and quantum anomaly in massive Dirac fermions

2021 ◽  
Vol 104 (24) ◽  
Author(s):  
Huan-Wen Wang ◽  
Bo Fu ◽  
Shun-Qing Shen
Keyword(s):  
Symmetry Breaking ◽  
Dirac Fermions ◽  
Helical Symmetry ◽  
Quantum Anomaly

scholarly journals Spin polarization of composite fermions and particle-hole symmetry breaking

2014 ◽  
Vol 90 (8) ◽  
Author(s):  
Yang Liu ◽  
S. Hasdemir ◽  
A. Wójs ◽  
J. K. Jain ◽  
L. N. Pfeiffer ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Spin Polarization ◽  
Composite Fermions

scholarly journals Quantum diffusion of massive Dirac fermions induced by symmetry breaking

2021 ◽  
Vol 104 (7) ◽  
Author(s):  
Ting Zhang ◽  
Chushun Tian ◽  
Ping Sheng
Keyword(s):  
Symmetry Breaking ◽  
Quantum Diffusion ◽  
Dirac Fermions

scholarly journals Cascade of phase transitions in a planar Dirac material

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Takuya Kanazawa ◽  
Mario Kieburg ◽  
Jacobus J.M. Verbaarschot
Keyword(s):  
Phase Diagram ◽  
Phase Transitions ◽  
Symmetry Breaking ◽  
Ground State ◽  
Chemical Potential ◽  
Three Dimensional ◽  
Dirac Fermions ◽  
First Order ◽  
First Order Phase ◽  
Parity Breaking

Abstract We investigate a model of interacting Dirac fermions in 2 + 1 dimensions with M flavors and N colors having the U(M)×SU(N ) symmetry. In the large-N limit, we find that the U(M) symmetry is spontaneously broken in a variety of ways. In the vacuum, when the parity-breaking flavor-singlet mass is varied, the ground state undergoes a sequence of M first-order phase transitions, experiencing M + 1 phases characterized by symmetry breaking U(M)→U(M − k)×U(k) with k ∈ {0, 1, 2, · · · , M}, bearing a close resemblance to the vacuum structure of three-dimensional QCD. At finite temperature and chemical potential, a rich phase diagram with first and second-order phase transitions and tricritical points is observed. Also exotic phases with spontaneous symmetry breaking of the form as U(3)→U(1)3, U(4)→U(2)×U(1)2, and U(5)→U(2)2×U(1) exist. For a large flavor-singlet mass, the increase of the chemical potential μ brings about M consecutive first-order transitions that separate the low-μ phase diagram with vanishing fermion density from the high-μ region with a high fermion density.

scholarly journals Tunable spin-valley coupling in layered polar Dirac metals

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Masaki Kondo ◽  
Masayuki Ochi ◽  
Tatsuhiro Kojima ◽  
Ryosuke Kurihara ◽  
Daiki Sekine ◽  
...  
Keyword(s):  
Transition Metal ◽  
Spin Polarization ◽  
Transition Metal Dichalcogenides ◽  
Spin Orbit Coupling ◽  
Dirac Fermions ◽  
Fermi Surfaces ◽  
Haas Oscillation ◽  
Spin Polarized ◽  
Metal Dichalcogenides ◽  
Inversion Asymmetry

AbstractIn non-centrosymmetric metals, spin-orbit coupling induces momentum-dependent spin polarization at the Fermi surfaces. This is exemplified by the valley-contrasting spin polarization in monolayer transition metal dichalcogenides with in-plane inversion asymmetry. However, the valley configuration of massive Dirac fermions in transition metal dichalcogenides is fixed by the graphene-like structure, which limits the variety of spin-valley coupling. Here, we show that the layered polar metal BaMnX2 (X = Bi, Sb) hosts tunable spin-valley-coupled Dirac fermions, which originate from the distorted X square net with in-plane lattice polarization. We found that BaMnBi2 has approximately one-tenth the lattice distortion of BaMnSb2, from which a different configuration of spin-polarized Dirac valleys is theoretically predicted. This was experimentally observed as a clear difference in the Shubnikov-de Haas oscillation at high fields between the two materials. The chemically tunable spin-valley coupling in BaMnX2 makes it a promising material for various spin-valleytronic devices.

scholarly journals R 3 c-type LnNiO3 (Ln = La, Ce, Nd, Pm, Gd, Tb, Dy, Ho, Er, Lu) half-metals with multiple Dirac cones: a potential class of advanced spintronic materials

IUCrJ ◽  
2019 ◽  
Vol 6 (6) ◽  
pp. 990-995 ◽  
Author(s):  
Xiaotian Wang ◽  
Guangqian Ding ◽  
Zhenxiang Cheng ◽  
Hongkuan Yuan ◽  
Xiao-Lin Wang ◽  
...  
Keyword(s):  
Physical Properties ◽  
Fermi Level ◽  
Spin Polarization ◽  
Three Dimensional ◽  
Electromagnetic Response ◽  
Dirac Fermions ◽  
Strongly Correlated ◽  
Half Metals ◽  
High Profile ◽  
Transport Carrier

In the past three years, Dirac half-metals (DHMs) have attracted considerable attention and become a high-profile topic in spintronics becuase of their excellent physical properties such as 100% spin polarization and massless Dirac fermions. Two-dimensional DHMs proposed recently have not yet been experimentally synthesized and thus remain theoretical. As a result, their characteristics cannot be experimentally confirmed. In addition, many theoretically predicted Dirac materials have only a single cone, resulting in a nonlinear electromagnetic response with insufficient intensity and inadequate transport carrier efficiency near the Fermi level. Therefore, after several attempts, we have focused on a novel class of DHMs with multiple Dirac crossings to address the above limitations. In particular, we direct our attention to three-dimensional bulk materials. In this study, the discovery via first principles of an experimentally synthesized DHM LaNiO3 with many Dirac cones and complete spin polarization near the Fermi level is reported. It is also shown that the crystal structures of these materials are strongly correlated with their physical properties. The results indicate that many rhombohedral materials with the general formula LnNiO3 (Ln = La, Ce, Nd, Pm, Gd, Tb, Dy, Ho, Er, Lu) in the space group R 3 c are potential DHMs with multiple Dirac cones.

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