Berry paramagnetism in the Dirac semimetal ZrTe5

AbstractDirac matters have attracted a lot of interest due to their unique band structure with linear band dispersions, which have great potential for technological applications. Recently, three-dimensional Dirac and Weyl semimetals have invoked distinctive phenomena originating from a non-trivial Berry phase. In this study, we prepare single crystals of TixZr1-xTe5 with a highly anisotropic Fermi surface. Our detailed electrical transport measurements reveal that the crystals show the Lifshitz transition, and Ti doping induces a band shift. Further quantum oscillation analyses demonstrate that the TixZr1-xTe5 crystals are 3D Dirac semimetals. Additionally, we observed a minimum temperature-dependent magnetic susceptibility, which is close to a peak position of electrical resistivity. This observation is interpreted in terms of the Berry paramagnetism. Our finding paves the way to determine a band topology by magnetism and also provides a platform to apply the Berry magnetism to Dirac semimetals.

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Tunable Berry curvature and transport crossover in topological Dirac semimetal KZnBi

npj Quantum Materials ◽

10.1038/s41535-021-00378-7 ◽

2021 ◽

Vol 6 (1) ◽

Author(s):

Junseong Song ◽

Byung Cheol Park ◽

Kyung Ik Sim ◽

Joonho Bang ◽

Sunghun Kim ◽

...

Keyword(s):

Three Dimensional ◽

Hall Resistance ◽

Rotational Axis ◽

Material System ◽

Chiral Fermion ◽

Quantum Phases ◽

Berry Curvature ◽

Dirac Semimetal ◽

Dirac Semimetals ◽

Single Material

AbstractTopological Dirac semimetals have emerged as a platform to engineer Berry curvature with time-reversal symmetry breaking, which allows to access diverse quantum states in a single material system. It is of interest to realize such diversity in Dirac semimetals that provides insight on correlation between Berry curvature and quantum transport phenomena. Here, we report the transition between anomalous Hall and chiral fermion states in three-dimensional topological Dirac semimetal KZnBi, which is demonstrated by tuning the direction and flux of Berry curvature. Angle-dependent magneto-transport measurements show that both anomalous Hall resistance and positive magnetoresistance are maximized at 0° between net Berry curvature and rotational axis. We find that the unexpected crossover of anomalous Hall resistance and negative magnetoresistance suddenly occurs when the angle reaches to ~70°, indicating that Berry curvature strongly correlates with quantum transports of Dirac and chiral fermions. It would be interesting to tune Berry curvature within other quantum phases such as topological superconductivity.

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Electronic structure of the candidate 2D Dirac semimetal SrMnSb2: a combined experimental and theoretical study

SciPost Physics ◽

10.21468/scipostphys.4.2.010 ◽

2018 ◽

Vol 4 (2) ◽

Cited By ~ 12

Author(s):

Shyama Varier Ramankutty ◽

Jans Henke ◽

Adriaan Schiphorst ◽

Rajah Nutakki ◽

Stephan Bron ◽

...

Keyword(s):

Electronic Structure ◽

Fermi Surface ◽

Theoretical Study ◽

Berry Phase ◽

Tight Binding ◽

Quantum Oscillation ◽

Great Promise ◽

Dirac Semimetal ◽

Arpes Data ◽

Good Agreement

SrMnSb_22 is suggested to be a magnetic topological semimetal. It contains square, 2D Sb planes with non-symmorphic crystal symmetries that could protect band crossings, offering the possibility of a quasi-2D, robust Dirac semi-metal in the form of a stable, bulk (3D) crystal. Here, we report a combined and comprehensive experimental and theoretical investigation of the electronic structure of SrMnSb_22, including the first ARPES data on this compound. SrMnSb_22 possesses a small Fermi surface originating from highly 2D, sharp and linearly dispersing bands (the ‘Y-states’) around the (0,/a)-point in kk-space. The ARPES Fermi surface agrees perfectly with that from bulk-sensitive Shubnikov de Haas data from the same crystals, proving the Y-states to be responsible for electrical conductivity in SrMnSb_22. DFT and tight binding (TB) methods are used to model the electronic states, and both show good agreement with the ARPES data. Despite the great promise of the latter, both theory approaches show the Y-states to be gapped above E_FF, suggesting trivial topology. Subsequent analysis within both theory approaches shows the Berry phase to be zero, indicating the non-topological character of the transport in SrMnSb_22, a conclusion backed up by the analysis of the quantum oscillation data from our crystals.

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Orbit topology analyzed from π phase shift of magnetic quantum oscillations in three-dimensional Dirac semimetal

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2023027118 ◽

2021 ◽

Vol 118 (29) ◽

pp. e2023027118

Author(s):

Sang-Eon Lee ◽

Myeong-jun Oh ◽

Sanghyun Ji ◽

Jinsu Kim ◽

Jin-Hyeon Jun ◽

...

Keyword(s):

Phase Shift ◽

Three Dimensional ◽

Dirac Fermion ◽

Quantum Oscillations ◽

Dirac Semimetal ◽

Single Orbit ◽

Dirac Materials ◽

Dirac Semimetals ◽

Cyclotron Mass ◽

Magnetic Quantum Oscillations

With the emergence of Dirac fermion physics in the field of condensed matter, magnetic quantum oscillations (MQOs) have been used to discern the topology of orbits in Dirac materials. However, many previous researchers have relied on the single-orbit Lifshitz–Kosevich (LK) formula, which overlooks the significant effect of degenerate orbits on MQOs. Since the single-orbit LK formula is valid for massless Dirac semimetals with small cyclotron masses, it is imperative to generalize the method applicable to a wide range of Dirac semimetals, whether massless or massive. This report demonstrates how spin-degenerate orbits affect the phases in MQOs of three-dimensional massive Dirac semimetal, NbSb2. With varying the direction of the magnetic field, an abrupt π phase shift is observed due to the interference between the spin-degenerate orbits. We investigate the effect of cyclotron mass on the π phase shift and verify its close relation to the phase from the Zeeman coupling. We find that the π phase shift occurs when the cyclotron mass is half of the electron mass, indicating the effective spin gyromagnetic ratio as gs = 2. Our approach is not only useful for analyzing MQOs of massless Dirac semimetals with a small cyclotron mass but also can be used for MQOs in massive Dirac materials with degenerate orbits, especially in topological materials with a sufficiently large cyclotron mass. Furthermore, this method provides a useful way to estimate the precise gs value of the material.

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Half-Dirac Semimetal and Quantum Anomalous Hall Effect in Kagome Cd2N3 Lattice

Nanoscale Advances ◽

10.1039/d0na00530d ◽

2020 ◽

Author(s):

Xinyang Li ◽

Weixiao Ji ◽

Peiji Wang ◽

Chang-wen Zhang

Keyword(s):

Hall Effect ◽

Quantum State ◽

Anomalous Hall Effect ◽

Topological Phases ◽

Dirac Semimetal ◽

Quantum Anomalous Hall Effect ◽

Dirac Materials ◽

Low Dimensionality ◽

Dirac Semimetals ◽

Topological Phases Of Matter

Half-Dirac semimetals (HDSs), which possess 100% spin-polarizations for Dirac materials, are highly desirable for exploring various topological phases of matter, as low-dimensionality opens unprecedented opportunities for manipulating the quantum state...

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Simulation of small-angle scattering curves by numerical Fourier transformation

Journal of Applied Crystallography ◽

10.1107/s002188980604550x ◽

2007 ◽

Vol 40 (1) ◽

pp. 16-25 ◽

Cited By ~ 37

Author(s):

Klaus Schmidt-Rohr

Keyword(s):

Form Factor ◽

Small Angle ◽

Fourier Transformation ◽

Three Dimensional ◽

Power Laws ◽

Numerical Approach ◽

Peak Position ◽

Two Dimensions ◽

Correlation Peak ◽

Scattering Intensity

A simple numerical approach for calculating theq-dependence of the scattering intensity in small-angle X-ray or neutron scattering (SAXS/SANS) is discussed. For a user-defined scattering density on a lattice, the scattering intensityI(q) (qis the modulus of the scattering vector) is calculated by three-dimensional (or two-dimensional) numerical Fourier transformation and spherical summation inqspace, with a simple smoothing algorithm. An exact and simple correction for continuous rather than discrete (lattice-point) scattering density is described. Applications to relatively densely packed particles in solids (e.g.nanocomposites) are shown, where correlation effects make single-particle (pure form-factor) calculations invalid. The algorithm can be applied to particles of any shape that can be defined on the chosen cubic lattice and with any size distribution, while those features pose difficulties to a traditional treatment in terms of form and structure factors. For particles of identical but potentially complex shapes, numerical calculation of the form factor is described. Long parallel rods and platelets of various cross-section shapes are particularly convenient to treat, since the calculation is reduced to two dimensions. The method is used to demonstrate that the scattering intensity from `randomly' parallel-packed long cylinders is not described by simple 1/qand 1/q4power laws, but at cylinder volume fractions of more than ∼25% includes a correlation peak. The simulations highlight that the traditional evaluation of the peak position overestimates the cylinder thickness by a factor of ∼1.5. It is also shown that a mix of various relatively densely packed long boards can produceI(q) ≃ 1/q, usually observed for rod-shaped particles, without a correlation peak.

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