arXiv subjects

Chenglong Jia

Publications and source records attributed to Chenglong Jia.

At least 37 records · Page 2Linked to original sources

arXiv2018

Topological thermal Hall effect driven by fluctuation of spin chirality in frustrated antiferromagnets

By revealing an underlying relation between the Dzyaloshinskii-Moriya interaction (DMI) and the scalar spin chirality, we develop the theory of magnon thermal Hall effects in antiferromagnetic systems. The dynamic fluctuation of the scalar chirality is shown to directly respond to the nontrivial topology of magnon bands. In materials such as the jarosites compounds KFe$_3$(OH)$_6$(SO$_4$)$_2$ and veseignite BaCu$_3$V$_2$O$_8$(OH)$_2$ in the presence of in-plane DMI, the time-reversal symmetry can be broken by the fluctuations of scalar chirality even in the case of coplanar $\mathbf{q}=0$ magnetic configuration. The spin-wave Hamiltonian is influenced by a fictitious magnetic flux determined by the in-plane DMI. Topological magnon bands and corresponding nonzero Chern numbers are presented without the need of a canted non-coplanar magnetic ordering. The canting angle dependence of thermal Hall conductivity is discussed in detail as well. These results offer a clear principle of chirality-driven topological effects in antiferromagnetically coupled systems.

cond-mat.str-el↗

arXiv2018

Time-resolved quantum spin transport through an Aharonov-Casher ring

After obtaining an exact analytical time-varying solution for the Aharonov-Casher conducting ring embedded in a textured static/dynamic electric field, we investigate the spin-resolved quantum transport in the structure. It is shown that the interference patterns are governed by not only the Aharonov-Casher geometry phase but also the instantaneous phase difference of spin precession through different traveling paths. This dynamic phase is determined by the strength of applied electric field and can have substantial effects on the charge/spin conductances, especially in the weak field regime as the period of spin precession comparable to that of the orbital motion. Our studies suggest that a low-frequency normal electric field with moderate strength possesses more degrees of freedom for manipulating the spin interference of incident electrons.

cond-mat.mes-hall↗

arXiv2017

Gate-controlled magnonic-assisted switching of magnetization in ferroelectric/ferromagnetic junctions

Interfacing a ferromagnet with a polarized ferroelectric gate generates a non-uniform, interfacial spin density coupled to the ferroelectric polarization allowing so for an electric field control of effective transversal field to magnetization. Here we study the dynamic magnetization switching behavior of such a multilayer system based on the Landau-Lifshitz-Baryakhtar equation, demonstrating that interfacial magnetoelectric coupling is utilizable as a highly localized and efficient tool for manipulating magnetism.

cond-mat.str-el↗

arXiv2016

Ultrafast transient dynamics in composite multiferroics

We investigate theoretically the dynamic multiferroic response of coupled ferroelectric/ferromagnetic composites upon excitation by a photo-induced acoustic strain pulse. Two magnetoelectric mechanisms are considered: interface strain- and charge-mediated magnetoelectric couplings. The former results in demagnetization, depolarization and repolarization within tens of picoseconds via respectively magnetostriction and piezoelectricity. Charge magnetoelectric interaction affects the ferroelectric/ferromagnetic feedback response leading to magnetization recovery. Experimental realization based on time-resolved x-ray diffraction is suggested. The findings indicate the potential of composite multiferroics for photo-steered, high-speed, multi-state electronic devices.

cond-mat.mes-hall↗

arXiv2013

Chargeless spin current for switching and coupling of domain walls in magnetic nanowires

The demonstration of the generation and control of a pure spin current (without net charge flow) by electric fields and/or temperature gradient has been an essential leap in the quest for low-power consumption electronics. The key issue of whether and how such a current can be utilized to drive and control information stored in magnetic domain walls (DWs) is still outstanding and is addressed here. We demonstrate that pure spin current acts on DWs in a magnetic stripe with an effective spin-transfer torque resulting in a mutual DWs separation dynamics and picosecond magnetization reversal. In addition, long-range ($\sim$ mm) antiferromagnetic DWs coupling emerges. If one DW is pinned by geometric constriction, the spin current induces a dynamical spin orbital interaction that triggers an internal electric field determined by $\vec{E} \sim \hat{e}_{x} \cdot (\vec{n}_{1} \times \vec{n}_{2})$ where $\vec{n}_{1/2}$ are the effective DWs orientations and $\hat{e}_{x} $ is their spatial separation vector. This leads to charge accumulation or persistent electric current in the wire. As DWs are routinely realizable and tuneable, the predicted effects bear genuine potential for power-saving spintronics devices.

cond-mat.mes-hall↗

arXiv2012

Piezoelectric control of the magnetic anisotropy via interface strain coupling in a composite multiferroic structure

We investigate theoretically the magnetic dynamics in a ferroelectric/ferromagnetic heterostructure coupled via strain-mediated magnetoelectric interaction. We predict an electric field-induced magnetic switching in the plane perpendicular to the magneto-crystalline easy axis, and trace this effect back to the piezoelectric control of the magnetoelastic coupling. We also investigate the magnetic remanence and the electric coercivity.

cond-mat.mes-hall↗

arXiv2012

Influence of the magnetoelectric coupling on the electric field induced magnetization reversal in a composite non-strained multiferroic chain

We study theoretically the multiferroic dynamics in a composite one-dimensional system consisting of BaTiO3 multiferroically coupled to an iron chain. The method treats the magnetization and the polarization as thermodynamic quantities describable via a combination of the Landau-Lifshits- Gilbert and the Ginzburg-Landau dynamics coupled via an additional term in the total free energy density. This term stems from the multiferroic interaction at the interface. For a wide range of strengths of this coupling we predict the possibility of obtaining a well-developed hysteresis in the ferromagnetic part of the system induced by an external electric field. The dependence of the reversal modes on the electric field frequency is also investigated and we predict a considerable stability of the magnetization reversal for frequencies in the range of 0.5 - 12 [GHz].

cond-mat.mtrl-sci↗

arXiv2011

Anisotropic thermoelectric effect in helimagnetic tunnel junctions

Thermoelectric transport across normal-metal/helical-multiferroic/ferromagnetic heterojunctions is theoretically investigated. We find a anisotropic charge and spin thermopower with a $C_{2v}$ symmetry. The angular dependence on the magnetization orientation of the ferromagnetic layer is substantiated by a phenomenological theory based on the symmetry of the effective spin-orbit interaction induced by the topology of the spiral magnetic order in the multiferroic barrier.

cond-mat.mes-hall↗

arXiv2011

Magnetic dynamics driven by the spin-current generated via spin-Seebeck effect

We consider the spin-current driven dynamics of a magnetic nanostructure in a conductive magnetic wire under a heat gradient in an open circuit, spin Seebeck effect geometry. It is shown that the spin-current scattering results in a spin-current torque acting on the nanostructure and leading to precession and displacement. The scattering leads also to a redistribution of the spin electrochemical potential along the wire resulting in a break of the polarity-reversal symmetry of the inverse spin Hall effect voltage with respect to the heat gradient inversion.

cond-mat.mes-hall↗

arXiv2011

Finite-size effects on the magnetoelectric response of field-driven ferroelectric/ferromagnetic chains

We study theoretically the coupled multiferroic dynamics of one-dimensional ferroelectric/ferromagnet chains driven by harmonic magnetic and electric fields as a function of the chain length. A linear magnetoelectric coupling is dominated by the spin-polarized screening charge at the interface. We performed Monte-Carlo simulations and calculations based on the coupled Landau-Lifshitz-Gilbert and Landau-Khalatnikov equations showing that the net magnetization and the total polarization of thin heterostructures, i.e. with up to ten ferroelectric and ferromagnetic sites counted from the interface, can be completely reversed by external electric and magnetic fields, respectively. However, for larger system solely a certain magnetoelectrical control can be achieved.

cond-mat.mes-hall↗

arXiv2011

Electric field-effect on thermodynamics of multiferroic spin chain

Thermodynamic properties of the helical spins with magnetoelectric coupling is simulated by Monte Carlo algorithm. It is shown that the spin-spin correlations are affected by the thermal fluctuations and the electric field. Results for the temperature-dependence of ferroelectric polarization and the susceptibility are also presented in connection with the multiferroic phase transition.

cond-mat.str-el↗

arXiv2010

Thermoelectric effect of multiferroic oxide interfaces

We investigate the thermoelectric properties of electrons at the interface of oxide heterostructure and in the presence of a multiferroic oxide with spiral spin order. We find there is no (spin) Hall current generated by the temperature gradient. A Seebeck effect is however present. Due to the magnetoelectric coupling, the charge and thermal conductivities are electrically controllable via the spin spiral helicity. Moreover, the thermopower exhibits a sign change when tuning electro-statically the carrier density.

cond-mat.mes-hall↗

arXiv2010

Magnetotransport and spin dynamics in an electron gas formed at oxide interfaces

We investigate the spin-dependent transport properties of a two-dimensional electron gas formed at oxides' interface in the presence of a magnetic field. We consider several scenarios for the oxides' properties, including oxides with co-linear or spiral magnetic and ferroelectric order. For spiral multiferroic oxides, the magnetoelectric coupling and the topology of the localized magnetic moments introduce additional, electric field controlled spin-orbit coupling that affects the magneto-oscillation of the current. An interplay of this spin-orbit coupling, the exchange field, and of the applied magnetic field results in a quantum, gate-controlled spin and charge Hall conductance.

cond-mat.mes-hall↗

arXiv2010

Coupled Spin-Phonon Excitations in Helical Multiferroics

Both the Dzyaloshiskii-Moriya interaction and the exchange-striction are shown to affect dynamically the magnetoelectric excitations in the perovskite multiferroic RMnO3. The exchange-striction results in a biquadratic interaction between the spins and the transverse phonons, giving rise to quantum fluctuations of the ferroelectric polarization P. This leads to low-lying phonon modes that are perpendicular to P and to the helical spins at small wave vector but are parallel to P at a wave vector close to the magnetic modulation vector. For spin-1/2 helimagnet, the local polarization can be completely reversed by the spin fluctuation, and so does the direction of the on-site spin chirality, which allows for a finite differential scattering intensity of polarized neutrons from a cycloidal magnet.

cond-mat.str-el↗

arXiv2010

Tunneling Anisotropic Magnetoresistance of Helimagnet Tunnel Junctions

We theoretically investigate the angular and spin dependent transport in normal-metal/helical-multiferroic/ferromagnetic heterojunctions. We find a tunneling anisotropic magnetoresistance (TAMR) effect due to the spiral magnetic order in the tunnel junction and to an effective spin-orbit coupling induced by the topology of the localized magnetic moments in the multiferroic spacer. The predicted TAMR effect is efficiently controllable by an external electric field due to the magnetoelectric coupling.

cond-mat.mes-hall↗

arXiv2009

Electrically controlled persistent spin currents at the interface of multiferroic oxides

We predict the appearance of a persistent spin current in a two-dimensional electron gas formed at the interface of multiferroic oxides with a transverse helical magnetic order. No charge current is generated. This is the result of an effective spin-orbit coupling generated by the topology of the oxide local magnetic moments. The effective coupling and the generated spin current depend linearly on the magnetic spiral helicity which, due to the magneto-electric coupling, is tunable by a transverse electric field offering thus a new mean for the generation of electrically controlled persistent spin currents.

cond-mat.mes-hall↗

arXiv2009

Multiferroic oxides-based flash-memory and spin-field-effect transistor

We propose a modified spin-field-effect transistor fabricated in a two dimensional electron gas (2DEG) formed at the surface of multiferroic oxides with a transverse helical magnetic order. The topology of the oxide local magnetic moments induces a resonant momentum-dependent effective spin-orbit interaction acting on 2DEG. We show that spin polarization dephasing is strongly suppressed which is crucial for functionality. The carrier spin precession phase depend linearly on the magnetic spiral helicity. The latter is electrically controllable by virtue of the magento-electric effect. We also suggest a flash-memory device based on this structure.

cond-mat.mtrl-sci↗

arXiv2009

z = 3 antiferromagnetic quantum critical point : U(1) slave-fermion theory of Anderson lattice model

We find the dynamical exponent $z = 3$ antiferromagnetic (AF) quantum critical point (QCP) in the heavy fermion quantum transition beyond the standard framework of the Hertz-Moriya-Millis theory with $z = 2$. Based on the U(1) slave-fermion representation of the Anderson lattice model, we show the continuous transition from an antiferromagnetic metal to a heavy fermion Fermi liquid, where the heavy fermion phase consists of two fluids, differentiated from the slave-boson theory. Thermodynamics and transport of the $z = 3$ AF QCP are shown to be consistent with the well known non-Fermi liquid physics such as the divergent Grüneisen ratio with an exponent 2/3 and temperature-linear resistivity. In particular, the uniform spin susceptibility turns out to diverge with an exponent 2/3, the hallmark of the $z = 3$ AF QCP described by deconfined bosonic spinons.

cond-mat.str-el↗