scholarly journals Electric manipulation of domain walls in magnetic Weyl semimetals via the axial anomaly

2021 ◽  
Vol 10 (5) ◽  
Author(s):  
Julia Hannukainen ◽  
Alberto Cortijo ◽  
Jens H Bardarson ◽  
Yago Ferreiros
Keyword(s):  
Domain Wall ◽  
Electric Field ◽  
Domain Walls ◽  
Direct Proof ◽  
Chiral Anomaly ◽  
Axial Anomaly ◽  
Domain Wall Dynamics ◽  
Weyl Semimetal ◽  
Electric And Magnetic Fields ◽  
Weyl Semimetals

We show how the axial (chiral) anomaly induces a spin torque on the magnetization in magnetic Weyl semimetals. The anomaly produces an imbalance in left- and right-handed chirality carriers when non-orthogonal electric and magnetic fields are applied. Such imbalance generates a spin density which exerts a torque on the magnetization, the strength of which can be controlled by the intensity of the applied electric field. We show how this results in an electric control of the chirality of domain walls, as well as in an improvement of the domain wall dynamics, by delaying the onset of the Walker breakdown. The measurement of the electric field mediated changes in the domain wall chirality would constitute a direct proof of the axial anomaly. Additionally, we show how quantum fluctuations of electronic Fermi arc states bound to the domain wall naturally induce an effective magnetic anisotropy, allowing for high domain wall velocities even if the intrinsic anisotropy of the magnetic Weyl semimetal is small.

scholarly journals Axion assisted Schwinger effect

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Valerie Domcke ◽  
Yohei Ema ◽  
Kyohei Mukaida
Keyword(s):  
Electric Field ◽  
Production Rate ◽  
Strong Electric Field ◽  
Background Field ◽  
Chiral Anomaly ◽  
Fermion Mass ◽  
Anomaly Equation ◽  
Electric And Magnetic Fields ◽  
Schwinger Effect ◽  
Momentum Transverse

Abstract We point out an enhancement of the pair production rate of charged fermions in a strong electric field in the presence of time dependent classical axion-like background field, which we call axion assisted Schwinger effect. While the standard Schwinger production rate is proportional to $$ \exp \left(-\pi \left({m}^2+{p}_T^2\right)/E\right) $$ exp − π m 2 + p T 2 / E , with m and pT denoting the fermion mass and its momentum transverse to the electric field E, the axion assisted Schwinger effect can be enhanced at large momenta to exp(−πm2/E). The origin of this enhancement is a coupling between the fermion spin and its momentum, induced by the axion velocity. As a non-trivial validation of our result, we show its invariance under field redefinitions associated with a chiral rotation and successfully reproduce the chiral anomaly equation in the presence of helical electric and magnetic fields. We comment on implications of this result for axion cosmology, focussing on axion inflation and axion dark matter detection.

Ferroelectric domain-wall logic units

2021 ◽  
Author(s):  
Jing Wang ◽  
Jing Ma ◽  
Houbing Huang ◽  
Ji Ma ◽  
Hasnain Jafri ◽  
...  
Keyword(s):  
Domain Wall ◽  
Electric Field ◽  
Domain Walls ◽  
Logic Gates ◽  
Piezoresponse Force Microscopy ◽  
Ferroelectric Domain ◽  
Conduction Path ◽  
Conductive Atomic Force Microscopy ◽  
Flexible Control ◽  
Force Microscopy

Abstract The electronic conductivities of ferroelectric domain walls have been extensively explored over the past decade for potential nanoelectronic applications. However, the realization of logic devices based on ferroelectric domain walls requires reliable and flexible control of the domain-wall configuration and conduction path. Here, we demonstrate electric-field-controlled stable and repeatable on-and-off switching of conductive domain walls within topologically confined vertex domains naturally formed in self-assembled ferroelectric nano-islands. Using a combination of piezoresponse force microscopy, conductive atomic force microscopy, and phase-field simulations, we show that on-off switching is accomplished through reversible transformations between charged and neutral domain walls via electric-field-controlled domain-wall reconfiguration. By analogy to logic processing, we propose programmable logic gates (such as NOT, OR, AND and their derivatives) and logic circuits (such as fan-out) based on reconfigurable conductive domain walls. Our work provides a potentially viable platform for programmable all-electric logic based on a ferroelectric domain-wall network with low energy consumption.

scholarly journals Axial anomaly generation by domain wall motion in Weyl semimetals

2020 ◽  
Vol 102 (24) ◽  
Author(s):  
Julia D. Hannukainen ◽  
Yago Ferreiros ◽  
Alberto Cortijo ◽  
Jens H. Bardarson
Keyword(s):  
Domain Wall ◽  
Wall Motion ◽  
Domain Wall Motion ◽  
Axial Anomaly ◽  
Weyl Semimetals

scholarly journals Electric field induced domain-wall dynamics: Depinning and chirality switching

2013 ◽  
Vol 88 (22) ◽  
Author(s):  
Pramey Upadhyaya ◽  
Ritika Dusad ◽  
Silas Hoffman ◽  
Yaroslav Tserkovnyak ◽  
Juan G. Alzate ◽  
...  
Keyword(s):  
Domain Wall ◽  
Electric Field ◽  
Domain Wall Dynamics

scholarly journals Electric-field-driven domain wall dynamics in perpendicularly magnetized multilayers

AIP Advances ◽  
2017 ◽  
Vol 7 (3) ◽  
pp. 035119 ◽  
Author(s):  
Diego López González ◽  
Yasuhiro Shirahata ◽  
Ben Van de Wiele ◽  
Kévin J. A. Franke ◽  
Arianna Casiraghi ◽  
...  
Keyword(s):  
Domain Wall ◽  
Electric Field ◽  
Domain Wall Dynamics

scholarly journals Positive Magnetoresistance and Chiral Anomaly in Exfoliated Type-II Weyl Semimetal Td-WTe2

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2755
Author(s):  
Rajdeep Adhikari ◽  
Soma Adhikari ◽  
Bogdan Faina ◽  
Marc Terschanski ◽  
Sophie Bork ◽  
...  
Keyword(s):  
Fermi Liquid ◽  
Topological Type ◽  
No Oxidation ◽  
Chiral Anomaly ◽  
Type Ii ◽  
Positive Magnetoresistance ◽  
Force Microscopy ◽  
Optical Reflectivity ◽  
Weyl Semimetal ◽  
Electric And Magnetic Fields

Layered van der Waals semimetallic Td-WTe2, exhibiting intriguing properties which include non-saturating extreme positive magnetoresistance (MR) and tunable chiral anomaly, has emerged as a model topological type-II Weyl semimetal system. Here, ∼45 nm thick mechanically exfoliated flakes of Td-WTe2 are studied via atomic force microscopy, Raman spectroscopy, low-T/high-μ0H magnetotransport measurements and optical reflectivity. The contribution of anisotropy of the Fermi liquid state to the origin of the large positive transverse MR⊥ and the signature of chiral anomaly of the type-II Weyl Fermions are reported. The samples are found to be stable in air and no oxidation or degradation of the electronic properties is observed. A transverse MR⊥∼1200 % and an average carrier mobility of 5000 cm2V−1s−1 at T=5K for an applied perpendicular field μ0H⊥=7T are established. The system follows a Fermi liquid model for T≤50K and the anisotropy of the Fermi surface is concluded to be at the origin of the observed positive MR. Optical reflectivity measurements confirm the anisotropy of the electronic behaviour. The relative orientation of the crystal axes and of the applied electric and magnetic fields is proven to determine the observed chiral anomaly in the in-plane magnetotransport. The observed chiral anomaly in the WTe2 flakes is found to persist up to T=120K, a temperature at least four times higher than the ones reported to date.

Electric field controlled domain wall dynamics and magnetic easy axis switching in liquid gated CoFeB/MgO films

2017 ◽  
Vol 122 (13) ◽  
pp. 133907 ◽  
Author(s):  
Y. T. Liu ◽  
S. Ono ◽  
G. Agnus ◽  
J.-P. Adam ◽  
S. Jaiswal ◽  
...  
Keyword(s):  
Domain Wall ◽  
Electric Field ◽  
Easy Axis ◽  
Domain Wall Dynamics ◽  
Magnetic Easy Axis ◽  
Axis Switching

scholarly journals Detect axial gauge fields with a calorimeter

2020 ◽  
Vol 3 (2) ◽  
Author(s):  
matteo Baggioli ◽  
Maxim N. Chernodub ◽  
Karl Landsteiner ◽  
Maria Vozmediano
Keyword(s):  
Specific Heat ◽  
Sound Wave ◽  
Experimental Verification ◽  
Density Wave ◽  
Gauge Fields ◽  
Axial Anomaly ◽  
Torsional Strain ◽  
Weyl Semimetal ◽  
Linear Behavior ◽  
Weyl Semimetals

Torsional strain in Weyl semimetals excites a unidirectional chiral density wave propagating in the direction of the torsional vector. This gapless excitation, named the chiral sound wave, is generated by a particular realization of the axial anomaly via the triple-axial (AAA) anomalous diagram. We show that the presence of the torsion-generated chiral sound leads to a linear behavior of the specific heat of a Weyl semimetal and to an enhancement of the thermal conductivty at experimentally accessible temperatures. We also demonstrate that such an elastic twist lowers the temperature of the sample, thus generating a new, anomalous type of elasto-calorific effect. Measurements of these thermodynamical effects will provide experimental verification of the exotic triple-axial anomaly as well as the reality of the elastic pseudomagnetic fields in Weyl semimetals.

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