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Mayes D, Farahmand F, Grossnickle M, Lohmann M, Aldosary M, Li J, Aji V, Shi J, Song JCW, Gabor NM. Mapping the intrinsic photocurrent streamlines through micromagnetic heterostructure devices. Proc Natl Acad Sci U S A 2023; 120:e2221815120. [PMID: 37722037 PMCID: PMC10523491 DOI: 10.1073/pnas.2221815120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 08/08/2023] [Indexed: 09/20/2023] Open
Abstract
Photocurrent in quantum materials is often collected at global contacts far away from the initial photoexcitation. This collection process is highly nonlocal. It involves an intricate spatial pattern of photocurrent flow (streamlines) away from its primary photoexcitation that depends sensitively on the configuration of current collecting contacts as well as the spatial nonuniformity and tensor structure of conductivity. Direct imaging to track photocurrent streamlines is challenging. Here, we demonstrate a microscopy method to image photocurrent streamlines through ultrathin heterostructure devices comprising platinum on yttrium iron garnet (YIG). We accomplish this by combining scanning photovoltage microscopy with a uniform rotating magnetic field. Here, local photocurrent is generated through a photo-Nernst type effect with its direction controlled by the external magnetic field. This enables the mapping of photocurrent streamlines in a variety of geometries that include conventional Hall bar-type devices, but also unconventional wing-shaped devices called electrofoils. In these, we find that photocurrent streamlines display contortion, compression, and expansion behavior depending on the shape and angle of attack of the electrofoil devices, much in the same way as tracers in a wind tunnel map the flow of air around an aerodynamic airfoil. This affords a powerful tool to visualize and characterize charge flow in optoelectronic devices.
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Affiliation(s)
- David Mayes
- Department of Physics and Astronomy, University of California, Riverside, CA92521
- Laboratory of Quantum Materials Optoelectronics, University of California, Riverside, CA92521
| | - Farima Farahmand
- Department of Physics and Astronomy, University of California, Riverside, CA92521
- Laboratory of Quantum Materials Optoelectronics, University of California, Riverside, CA92521
| | - Maxwell Grossnickle
- Department of Physics and Astronomy, University of California, Riverside, CA92521
- Laboratory of Quantum Materials Optoelectronics, University of California, Riverside, CA92521
| | - Mark Lohmann
- Department of Physics and Astronomy, University of California, Riverside, CA92521
| | - Mohammed Aldosary
- Department of Physics and Astronomy, University of California, Riverside, CA92521
| | - Junxue Li
- Department of Physics and Astronomy, University of California, Riverside, CA92521
| | - Vivek Aji
- Department of Physics and Astronomy, University of California, Riverside, CA92521
| | - Jing Shi
- Department of Physics and Astronomy, University of California, Riverside, CA92521
| | - Justin C. W. Song
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore637371, Singapore
| | - Nathaniel M. Gabor
- Department of Physics and Astronomy, University of California, Riverside, CA92521
- Laboratory of Quantum Materials Optoelectronics, University of California, Riverside, CA92521
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Gooth J, Galeski S, Meng T. Quantum-Hall physics and three dimensions. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2023; 86:044501. [PMID: 36735956 DOI: 10.1088/1361-6633/acb8c9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Accepted: 02/03/2023] [Indexed: 06/18/2023]
Abstract
The discovery of the quantum Hall effect (QHE) in 1980 marked a turning point in condensed matter physics: given appropriate experimental conditions, the Hall conductivityσxyof a two-dimensional electron system is exactly quantized. But what happens to the QHE in three dimensions (3D)? Experiments over the past 40 years showed that some of the remarkable physics of the QHE, in particular plateau-like Hall conductivitiesσxyaccompanied by minima in the longitudinal resistivityρxx, can also be found in 3D materials. However, since typicallyρxxremains finite and a quantitative relation betweenσxyand the conductance quantume2/hcould not be established, the role of quantum Hall physics in 3D remains unsettled. Following a recent series of exciting experiments, the QHE in 3D has now returned to the center stage. Here, we summarize the leap in understanding of 3D matter in magnetic fields emerging from these experiments.
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Affiliation(s)
- Johannes Gooth
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
- Physikalisches Institut, Rheinische Friedrich-Wilhelms-Universität, Nußalle 12, 53115 Bonn, Germany
| | - Stanislaw Galeski
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
- Physikalisches Institut, Rheinische Friedrich-Wilhelms-Universität, Nußalle 12, 53115 Bonn, Germany
| | - Tobias Meng
- Institute of Theoretical Physics and Würzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, Dresden 01062, Germany
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Nonlinear nanoelectrodynamics of a Weyl metal. Proc Natl Acad Sci U S A 2021; 118:2116366118. [PMID: 34819380 DOI: 10.1073/pnas.2116366118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/25/2021] [Indexed: 11/18/2022] Open
Abstract
Chiral Weyl fermions with linear energy-momentum dispersion in the bulk accompanied by Fermi-arc states on the surfaces prompt a host of enticing optical effects. While new Weyl semimetal materials keep emerging, the available optical probes are limited. In particular, isolating bulk and surface electrodynamics in Weyl conductors remains a challenge. We devised an approach to the problem based on near-field photocurrent imaging at the nanoscale and applied this technique to a prototypical Weyl semimetal TaIrTe4 As a first step, we visualized nano-photocurrent patterns in real space and demonstrated their connection to bulk nonlinear conductivity tensors through extensive modeling augmented with density functional theory calculations. Notably, our nanoscale probe gives access to not only the in-plane but also the out-of-plane electric fields so that it is feasible to interrogate all allowed nonlinear tensors including those that remained dormant in conventional far-field optics. Surface- and bulk-related nonlinear contributions are distinguished through their "symmetry fingerprints" in the photocurrent maps. Robust photocurrents also appear at mirror-symmetry breaking edges of TaIrTe4 single crystals that we assign to nonlinear conductivity tensors forbidden in the bulk. Nano-photocurrent spectroscopy at the boundary reveals a strong resonance structure absent in the interior of the sample, providing evidence for elusive surface states.
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Kurkov M, Vassilevich D. How Many Surface Modes Does One See on the Boundary of a Dirac Material? PHYSICAL REVIEW LETTERS 2020; 124:176802. [PMID: 32412251 DOI: 10.1103/physrevlett.124.176802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 04/14/2020] [Indexed: 06/11/2023]
Abstract
We present full expressions for the surface part of polarization tensor of a Dirac fermion confined in a half-space in 3+1 dimensions. We compare this tensor to the polarization tensor of eventual surface mode (which is a 2+1 dimensional Dirac fermion) and find essential differences in the conductivities in both Hall and normal sectors. Thus, the interaction with electromagnetic field near the boundary differs significantly in the full model and in the effective theory for the surface mode.
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Affiliation(s)
- Maxim Kurkov
- Dipartimento di Fisica "Ettore Pancini," Università di Napoli Federico II, Napoli, Complesso Univ. Monte S. Angelo, Via Cintia, I-80126 Napoli, Italy
- INFN, Sezione di Napoli, Via Cintia, 80126 Napoli, Italy
| | - Dmitri Vassilevich
- CMCC, Universidade Federal do ABC, CEP 09210-80 Santo André, São Paulo, Brazil
- Physics Department, Tomsk State University, 634050 Tomsk, Russia
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