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Quantized spin pump on helical edge states of a topological insulator. Sci Rep 2019; 9:3378. [PMID: 30833644 PMCID: PMC6399345 DOI: 10.1038/s41598-019-39002-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 12/31/2018] [Indexed: 11/08/2022] Open
Abstract
We report a theoretical study of the quantized spin pump in a traditional quantum pump device that is based on the helical edge states of a quantum spin Hall insulator. By introducing two time-dependent magnetizations out of phase as the pumping parameters, we found that when the Fermi energy resides in the energy gap opened by magnetization, an integer number of charges or spins can be pumped out in a pumping cycle and ascribed to the possible topological interface state born in between the two pumping potentials. The quantized pump current can be fully spin-polarized, spin-unpolarized, or pure spin current while its direction can be abruptly reversed by some system parameters such as the pumping phase and local gate voltage. Our findings may shed light on generation of a quantized spin pump.
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Herasymenko Y, Snizhko K, Gefen Y. Universal Quantum Noise in Adiabatic Pumping. PHYSICAL REVIEW LETTERS 2018; 120:226802. [PMID: 29906130 DOI: 10.1103/physrevlett.120.226802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 04/23/2018] [Indexed: 06/08/2023]
Abstract
We consider charge pumping in a system of parafermions, implemented at fractional quantum Hall edges. Our pumping protocol leads to a noisy behavior of the pumped current. As the adiabatic limit is approached, not only does the noisy behavior persist but the counting statistics of the pumped current becomes robust and universal. In particular, the resulting Fano factor is given in terms of the system's topological degeneracy and the pumped quasiparticle charge. Our results are also applicable to the more conventional Majorana fermions.
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Affiliation(s)
- Yaroslav Herasymenko
- Instituut-Lorentz for Theoretical Physics, Leiden University, Leiden, CA NL-2333, Netherlands
| | - Kyrylo Snizhko
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, 76100 Israel
| | - Yuval Gefen
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, 76100 Israel
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Napitu BD, Thijssen JM. Adiabatic and non-adiabatic charge pumping in a single-level molecular motor. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:275301. [PMID: 26086210 DOI: 10.1088/0953-8984/27/27/275301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We propose a design for realizing quantum charge pump based on a recent proposal for a molecular motor (Seldenthuis J S et al 2010 ACS Nano 4 6681). Our design is based on the presence of a moiety with a permanent dipole moment which can rotate, thereby modulating the couplings to metallic contacts at both ends of the molecule. Using the non-equilibrium Keldysh Green's function formalism (NEGF), we show that our design indeed generates a pump current. In the non-interacting pump, the variation of frequency from adiabatic to non-adiabatic regime, can be used to control the direction as well as the amplitude of the average current. The effect of Coulomb interaction is considered within the first- and the second- order perturbation. The numerical implementation of the scheme is quite demanding, and we develop an analytical approximation to obtain a speed-up giving results within a reasonable time. We find that the amplitude of the average pumped current can be controlled by both the driving frequency and the Coulomb interaction. The direction of of pumped current is shown to be determined by the phase difference between left and right anchoring groups.
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Affiliation(s)
- B D Napitu
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628CJ, Delft The Netherlands
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4
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Zhang SF, Zhu W. The limit spin current in a time-dependent Rashba spin-orbit coupling system. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:075302. [PMID: 23328536 DOI: 10.1088/0953-8984/25/7/075302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The generation of spin current in a one dimensional electron gas (1DEG) system is studied, where the Rashba spin-orbit coupling (RSOC) is modulated by a time-varying gate voltage. With a simple unitary transformation, we show the appearance of an additional spin-dependent potential which results in a spin-dependent effective electric field. We include the scattering interaction by taking a relaxation approximation. The formula for the induced spin current is derived, the limit value accessible by time-varying RSOC is obtained and the order of magnitude is estimated. We find that the maximum of a pulsed spin current can reach that limit value. The results in 1DEG are extended to 2DEG. In addition, we study the spin current in a metal-quantum dot-metal system.
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Affiliation(s)
- Shu-feng Zhang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
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Zhang Q, Lin Z, Chan KS. Pure spin current generation in monolayer graphene by quantum pumping. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:075302. [PMID: 22297657 DOI: 10.1088/0953-8984/24/7/075302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We study a method to generate pure spin current in monolayer graphene over a wide range of Fermi energy by adiabatic quantum pumping. The device consists of three gate electrodes and two ferromagnetic strips, which induce a spin-splitting in the graphene through the proximity effect. A pure spin current is generated by applying two periodic oscillating gate voltages. We find that the pumped pure spin current is a sensitive oscillatory function of the Fermi energy. Large spin currents can be found at Fermi energies where there are Fabry-Perot resonances in the barriers. Furthermore, we analyze the effects of the parameters of the system on the pumped currents. Our predicted pumped spin current can be of the order of 100 nA which is measurable using the current technology. The proposed method is useful in the realization of graphene spintronic devices.
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Affiliation(s)
- Qingtian Zhang
- Department of Physics, University of Science and Technology of China, Hefei, People's Republic of China
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Feng H, Zhuo R, Chen J, Yan D, Feng J, Li H, Cheng S, Wu Z, Wang J, Yan P. Synthesis, Characterization, and Microwave Absorption Property of the SnO2Nanowire/Paraffin Composites. NANOSCALE RESEARCH LETTERS 2009; 4:1452-1457. [PMID: 20651925 PMCID: PMC2893785 DOI: 10.1007/s11671-009-9419-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Accepted: 08/12/2009] [Indexed: 05/29/2023]
Abstract
In this article, SnO2nanowires (NWs) have been prepared and their microwave absorption properties have been investigated in detail. Complex permittivity and permeability of the SnO2NWs/paraffin composites have been measured in a frequency range of 0.1-18 GHz, and the measured results are compared with that calculated from effective medium theory. The value of maximum reflection loss for the composites with 20 vol.% SnO2NWs is approximately -32.5 dB at 14 GHz with a thickness of 5.0 mm.
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Affiliation(s)
- Ht Feng
- School of Physical Science and Technology, Lanzhou University, 730000, Lanzhou, China.
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Fioretto D, Silva A. Phase coherence, inelastic scattering, and interaction corrections in pumping through quantum dots. PHYSICAL REVIEW LETTERS 2008; 100:236803. [PMID: 18643534 DOI: 10.1103/physrevlett.100.236803] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Indexed: 05/26/2023]
Abstract
Adiabatic quantum pumping in noninteracting, phase coherent quantum dots is elegantly described by Brouwer's formula. Interactions within the dot, while suppressing phase coherence, make Brouwer's formalism inapplicable. In this Letter, we discuss the nature of the physical processes forcing a description of pumping beyond Brouwer's formula, and develop, using a controlled adiabatic expansion, a useful formalism to study the effect of interactions within a generic perturbative scheme. The pumped current consists of a first contribution, analogous to Brouwer's formula and accounting for the remanent coherence, and of interaction corrections describing inelastic scattering. We apply the formalism to study the effect of interaction with a bosonic bath on a resonant level pump and discuss the robustness of the quantization of the pumped charge in turnstile cycles.
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Affiliation(s)
- Davide Fioretto
- Dipartimento di Fisica, Universita' degli Studi di Milano, Milano, Italy
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Zhang JQ, Vitkalov S, Kvon ZD, Portal JC, Wieck A. Directed electron transport through a ballistic quantum dot under microwave radiation. PHYSICAL REVIEW LETTERS 2006; 97:226807. [PMID: 17155830 DOI: 10.1103/physrevlett.97.226807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Indexed: 05/12/2023]
Abstract
Rectification of microwave radiation by asymmetric ballistic dot is studied at different frequencies (1-40 GHz), temperatures, and magnetic fields. Dramatic reduction of the rectification is found in magnetic fields at which the cyclotron radius of electron orbits at the Fermi level is less than the size of the dot. With respect to the magnetic field, both symmetric and antisymmetric contributions to the rectification are presented. The symmetric part changes significantly with microwave frequency omega at omegatau_{f}>/=1, where tau_{f} is the time of the ballistic electron flight across the dot. The results lead consistently towards the ballistic origin of the effect, and can be explained by strongly nonlocal electron response to the microwave electric field, which affects both speed and direction of the electron motion inside the dot.
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Affiliation(s)
- Jing-Qiao Zhang
- Physics Department, City College of the City University of New York, New York 10031, USA
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Sela E, Oreg Y. Adiabatic pumping in interacting systems. PHYSICAL REVIEW LETTERS 2006; 96:166802. [PMID: 16712255 DOI: 10.1103/physrevlett.96.166802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2005] [Indexed: 05/09/2023]
Abstract
A dc current can be pumped through an interacting system by periodically varying two independent parameters such as the magnetic field and a gate potential. We present a general expression for the adiabatic pumping current in interacting systems, written in terms of instantaneous properties of the system at equilibrium, and find the limits of its applicability. This expression generalizes the scattering approach for noninteracting particles. We apply our formula for a quantum critical system that exhibits the two-channel Kondo effect, where single particle excitations are not well defined. We find that if the quantum critical point is contained in the pumping trajectory, the pumped spin between the channels approaches h, and if it is not contained in the trajectory, the spin approaches zero when the temperature T --> 0. We discuss the non-Fermi liquid features of this system at finite T.
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Affiliation(s)
- Eran Sela
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, 76100, Israel
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Kim SW, Choi MS. Decoherence-driven quantum transport. PHYSICAL REVIEW LETTERS 2005; 95:226802. [PMID: 16384251 DOI: 10.1103/physrevlett.95.226802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2005] [Indexed: 05/05/2023]
Abstract
We propose a new mechanism to generate a dc current of particles at zero bias based on a noble interplay between coherence and decoherence. We show that a dc current arises if the transport process in one direction is maintained coherent while the process in the opposite direction is incoherent. We provide possible implementations of the idea using an atomic Michelson interferometer and a ring interferometer.
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Affiliation(s)
- Sang Wook Kim
- Department of Physics Education, Pusan National University, Busan 609-735, Korea.
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Watson SK, Potok RM, Marcus CM, Umansky V. Experimental realization of a quantum spin pump. PHYSICAL REVIEW LETTERS 2003; 91:258301. [PMID: 14754164 DOI: 10.1103/physrevlett.91.258301] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2003] [Indexed: 05/24/2023]
Abstract
We demonstrate the operation of a quantum spin pump based on cyclic radio-frequency excitation of a GaAs quantum dot, including the ability to pump pure spin without pumping charge. The device takes advantage of bidirectional mesoscopic fluctuations of pumped current, made spin dependent by the application of an in-plane Zeeman field. Spin currents are measured by placing the pump in a focusing geometry with a spin-selective collector.
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Affiliation(s)
- Susan K Watson
- Department of Physics, Middlebury College, Middlebury, Vermont 05753, USA
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DiCarlo L, Marcus CM, Harris JS. Photocurrent, rectification, and magnetic field symmetry of induced current through quantum dots. PHYSICAL REVIEW LETTERS 2003; 91:246804. [PMID: 14683146 DOI: 10.1103/physrevlett.91.246804] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2003] [Indexed: 05/24/2023]
Abstract
We report mesoscopic dc current generation in an open chaotic quantum dot with ac excitation applied to one of the shape-defining gates. For excitation frequencies large compared to the inverse dwell time of electrons in the dot (i.e., GHz), we find mesoscopic fluctuations of induced current that are fully asymmetric in the applied perpendicular magnetic field, as predicted by recent theory. Conductance, measured simultaneously, is found to be symmetric in field. In the adiabatic (i.e., MHz) regime, in contrast, the induced current is always symmetric in field, suggesting its origin is mesoscopic rectification.
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Affiliation(s)
- L DiCarlo
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
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Polianski ML, Brouwer PW. Scattering matrix ensemble for time-dependent transport through a chaotic quantum dot. ACTA ACUST UNITED AC 2003. [DOI: 10.1088/0305-4470/36/12/321] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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15
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Chalaev OL, Kravtsov VE. Aharonov-bohm magnetization of mesoscopic rings caused by inelastic relaxation. PHYSICAL REVIEW LETTERS 2002; 89:176601. [PMID: 12398692 DOI: 10.1103/physrevlett.89.176601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2002] [Indexed: 05/24/2023]
Abstract
The magnetization of a system of many mesoscopic rings under nonequilibrium conditions is considered. The corresponding disorder-averaged current in a ring I(phi) is shown to be a sum of the "thermodynamic" and "kinetic" contributions both resulting from the electron-electron interaction. The thermodynamic part can be expressed through the diagonal matrix elements J(micro micro) of the current operator in the basis of exact many-body eigenstates and is a generalization of the equilibrium persistent current. The novel kinetic part is present only out of equilibrium and is governed by the off-diagonal matrix elements J(micro nu). It has drastically different temperature and magnetic field behavior.
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Affiliation(s)
- O L Chalaev
- International School of Advanced Studies, via Beirut 4, 34014 Trieste, Italy
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Mucciolo ER, Chamon C, Marcus CM. Adiabatic quantum pump of spin-polarized current. PHYSICAL REVIEW LETTERS 2002; 89:146802. [PMID: 12366064 DOI: 10.1103/physrevlett.89.146802] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2001] [Indexed: 05/23/2023]
Abstract
We propose a mechanism by which an open quantum dot driven by two ac (radio frequency) gate voltages in the presence of a moderate in-plane magnetic field generates a spin-polarized, phase-coherent dc current. The idea combines adiabatic, nonquantized (but coherent) pumping through periodically modulated external parameters and the strong fluctuations of the electron wave function existent in chaotic cavities. We estimate that the spin polarization of the current can be observed for temperatures and Zeeman splitting energies of the order of the single-particle mean level spacing.
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Affiliation(s)
- Eduardo R Mucciolo
- Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, C.P. 38071, 22452-970 Rio de Janeiro, Brazil
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Makhlin Y, Mirlin AD. Counting statistics for arbitrary cycles in quantum pumps. PHYSICAL REVIEW LETTERS 2001; 87:276803. [PMID: 11800907 DOI: 10.1103/physrevlett.87.276803] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2001] [Indexed: 05/23/2023]
Abstract
We study noise-related properties of current in adiabatic pumps. A symmetry of the problem allows us to relate the statistics of charge transport in the case of one-channel leads to the geometry of loops on a sphere (for many channels on a higher-dimensional manifold). This provides a unifying framework, which simplifies analysis of transport in various realizations of pumps. For each pumping cycle, the average current and its minimal variance are given by the areas enclosed by the corresponding loop on the sphere and on a minimal surface (soap film) spanned by this loop. We formulate conditions for quantization of the pumped charge.
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Affiliation(s)
- Y Makhlin
- Institut für Theoretische Festkörperphysik, Universität Karlsruhe, 76128 Karlsruhe, Germany
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Astumian RD, Derényi I. Towards a chemically driven molecular electron pump. PHYSICAL REVIEW LETTERS 2001; 86:3859-3862. [PMID: 11329342 DOI: 10.1103/physrevlett.86.3859] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2000] [Indexed: 05/23/2023]
Abstract
Charge can be pumped through a tiny gated portal from a reservoir at low electrochemical potential to one at the same or higher electrochemical potential by cyclically modulating the portal and gate energies. A theoretically and experimentally well established mechanism is Thouless adiabatic pumping, achieved by a precisely timed out-of-phase modulation of at least two parameters of the system. Here we show that stochastic modulation between two configurations of gate and portal energies can drive efficient pumping by a different, nonadiabatic, mechanism that may provide a basis for chemically driven electron pumping through a molecular wire.
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Affiliation(s)
- R D Astumian
- Department of Physics, University of Maine, Orono, Maine 04469-5709, USA.
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Andreev A, Kamenev A. Counting statistics of an adiabatic pump. PHYSICAL REVIEW LETTERS 2000; 85:1294-1297. [PMID: 10991535 DOI: 10.1103/physrevlett.85.1294] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2000] [Indexed: 05/23/2023]
Abstract
We use the Schwinger-Keldysh formalism to derive the charge counting statistics of an adiabatic pump based on an open quantum dot. The distribution function of the transmitted charge in terms of the time-dependent S matrix is obtained. It is applied to a few simple examples of the pumping cycles. By a chiral gauge transformation the problem is mapped onto a problem of pumping by voltage pulses. The role of the chiral anomaly arising in this mapping is emphasized. Conditions for the ideal noiseless quantized pump are discussed.
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Affiliation(s)
- A Andreev
- Department of Physics, CB 390, University of Colorado, Boulder, Colorado 80303, USA
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Zhou F, Spivak B, Taniguchi N, Altshuler BL. Giant Microwave Absorption in Metallic Grains: Relaxation Mechanism. PHYSICAL REVIEW LETTERS 1996; 77:1958-1961. [PMID: 10061821 DOI: 10.1103/physrevlett.77.1958] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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