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Abstract Nonlinear transport is a unique functionality of noncentrosymmetric systems, which reflects profound physics, such as spin-orbit interaction, superconductivity and band geometry. However, it remains highly challenging to enhance the nonreciprocal transport for promising rectification devices. Here, we observe a light-induced giant enhancement of nonreciprocal transport at the superconducting and epitaxial CaZrO3/KTaO3 (111) interfaces. The nonreciprocal transport coefficient undergoes a giant increase with three orders of magnitude up to 105 A−1 T−1. Furthermore, a strong Rashba spin-orbit coupling effective field of 14.7 T is achieved with abundant high-mobility photocarriers under ultraviolet illumination, which accounts for the giant enhancement of nonreciprocal transport coefficient. Our first-principles calculations further disclose the stronger Rashba spin-orbit coupling strength and the longer relaxation time in the photocarrier excitation process, bridging the light-property quantitative relationship. Our work provides an alternative pathway to boost nonreciprocal transport in noncentrosymmetric systems and facilitates the promising applications in opto-rectification devices and spin-orbitronic devices.

Orbital currents play a fundamental role in a wide range of transport phenomena. Recently, the discovery of a novel chiral orbital current state in the ferrimagnetic nodal-line semiconductor Mn3Si2Te6 has attracted significant interest, supported by anomalous I–V characteristics and time-dependent bistable switching. However, the direct experimental verifications, combining electrical transport and magnetic measurement, that detect the variation of the magnetic properties vs the current are still rare. Here, we investigate the transport properties of Mn3Si2Te6 and track the current-induced dynamics of the magnetic moment. Reflective magnetic circular dichroism reveals that significant alterations in Mn3Si2Te6 magnetoresistance in response to an electric field are necessarily coupled with a magnetic phase transition, establishing a rare correlation. Our findings indicate the predominance of magnetic chiral orbital currents in the colossal angular magnetoresistance effect, offering a unique platform for advanced studies in orbital magnetism.

Abstract Naturally existing in-plane hyperbolic polaritons and the associated optical topological transitions, which avoid the nano-structuring to achieve hyperbolicity, can outperform their counterparts in artificial metasurfaces. Such plasmon polaritons are rare, but experimentally revealed recently in WTe2 van der Waals thin films. Different from phonon polaritons, hyperbolic plasmon polaritons originate from the interplay of free carrier Drude response and interband transitions, which promise good intrinsic tunability. However, tunable in-plane hyperbolic plasmon polariton and its optical topological transition of the isofrequency contours to the elliptic topology in a natural material have not been realized. Here we demonstrate the tuning of the optical topological transition through Mo doping and temperature. The optical topological transition energy is tuned over a wide range, with frequencies ranging from 429 cm−1 (23.3 microns) for pure WTe2 to 270 cm−1 (37.0 microns) at the 50% Mo-doping level at 10 K. Moreover, the temperature-induced blueshift of the optical topological transition energy is also revealed, enabling active and reversible tuning. Surprisingly, the localized surface plasmon resonance in skew ribbons shows unusual polarization dependence, accurately manifesting its topology, which renders a reliable means to track the topology with far-field techniques. Our results open an avenue for reconfigurable photonic devices capable of plasmon polariton steering, such as canaling, focusing, and routing, and pave the way for low-symmetry plasmonic nanophotonics based on anisotropic natural materials.

Available intrinsic magnetic topological insulators are rare. Here, the authors study the electronic and magnetic properties of Mn(Sb x Bi(1-x))2Te4 bulks and thin flakes, revealing intrinsic magnetic topological insulator phase in the phase diagram.

Topological insulators and their characteristics are among the most highly studied areas in condensed matter physics. Bi2Se3 nanocrystals were synthesized via chemical vapor deposition at different temperatures on a silicon substrate with a gold catalyst. The effects of temperature on the obtained Bi2Se3 nanocrystals were systematically investigated. The size and length of Bi2Se3 nanocrystals change when the temperature increases from 500 °C to 600 °C. We found that the crystallization quality of the Bi2Se3 nanocrystals synthesized at 560 °C is optimal. At this temperature, we can get the desired thickness and length of the nanocrystals, which is quite suitable for nanoscale fabrication.

Large unsaturated magnetoresistance (XMR) with magnitude ∼103% is observed in topological insulator candidate TaSe3 from our high field (up to 38 T) measurements. Two oscillation modes, associated with one hole pocket and two electron pockets in the bulk, respectively, are detected from our Shubnikov-de Hass measurements, consistent with our first-principles calculations. With the detailed Hall measurements performed, our two-band model analysis exhibits an imperfect density ratio nh/ne ≈ 0.9 at T < 20 K, which suggests that the carrier compensations account for the XMR in TaSe3.

The transition metal dichalcogenide Ir1−xPtxTe2 displays both superconductivity and a topological band structure. Using angle-resolved photoemission spectroscopy, we obtain a comprehensive understanding of the three-dimensional electronic structure in the normal state of Ir1−xPtxTe2 for doping levels from x = 0.1 to 0.4, which spans the composition range of a superconducting state to a non-superconducting state. Many features of the electronic structure can be attributed to strong Te–Te interactions between the layers of the layered crystal structure and can be resolved by photon energy dependent measurements. We demonstrate that the type-II Dirac fermions can be successfully tuned via Pt doping, where the Dirac point lies close to the Fermi level for x = 0.1. The band evolution vs doping provides a clearer understanding of the relationship between the superconductivity and electronic structure. In addition, the β band in the superconducting samples locates the system close to a type-II van Hove singularity, where spin triplet paring symmetry has been predicted. Our results provide a comprehensive understanding of the band structure of Ir1−xPtxTe2, and we discuss the possibilities of the existence of topological superconductivity in this system.

The topological surface states usually appear in pairs in a topological insulator, with one on the top surface and the other on the bottom surface. Here, Zhang et al. utilize Co cluster to induce a Zeeman gap on one surface through antiferromagnetic exchange coupling, and observe a quasi-half-integer plateau, suggesting the parity anomaly of Dirac fermions.

A lateral heterojunction of topologicalinsulator Sb2Te3/Bi2Te3was successfully synthesized using a two-step solvothermal method.The two crystalline components were separated well by a sharp lattice-matchedinterface when the optimized procedure was used. Inspecting the heterojunctionusing high-resolution transmission electron microscopy showed thatepitaxial growth occurred along the horizontal plane. The semiconductingtemperature-resistance curve and crossjunction rectification wereobserved, which reveal a staggered-gap lateral heterojunction witha small junction voltage. Quantum correction from the weak antilocalizationreveals the well-maintained transport of the topological surface state.This is appealing for a platform for spin filters and one-dimensionaltopological interface states. [ABSTRACT FROM AUTHOR]

We fabricated nanodevices from MoxW1−xTe2 (x = 0, 0.07, 0.35), and conducted a systematic comparative study of their electrical transport. Magnetoresistance measurements show that Mo doping can significantly suppress mobility and magnetoresistance. The results for the analysis of the two band model show that doping with Mo does not break the carrier balance. Through analysis of Shubnikov–de Haas oscillations, we found that Mo doping also has a strong suppressive effect on the quantum oscillation of the sample, and the higher the ratio of Mo, the fewer pockets were observed in our experiments. Furthermore, the effective mass of electron and hole increases gradually with increasing Mo ratio, while the corresponding quantum mobility decreases rapidly. [ABSTRACT FROM AUTHOR]

We report on a systematic study of type-II Dirac fermions in a layered crystal of PdTe2. De Haas-van Alphen oscillations show a small Fermi-surface pocket with a cross section of 0.077nm-2 with a nontrivial Berry phase. First-principles calculation reveals that the nontrivial Berry phase originates from a hole pocket formed by the tilted Dirac cone. In addition, the band dispersion measured with angle-resolved photoemission spectroscopy is found to be consistent with that of a type-II Dirac cone dispersion. We propose that PdTe2 is an improved platform to host topological superconductors. [ABSTRACT FROM AUTHOR]