Fingerprints of spin-current physics on magnetoelectric response in the spin-$1/2$ magnet Ba${}_2$CuGe${}_2$O${}_7$

Abstract

The single-site anisotropy vanishes for the spin-1/2 as a consequence of Kramers degeneracy. We argue that similar property holds for the magnetically induced electric polarization P, which should depend only on the relative orientation of spins in the bonds but not on the direction of each individual spin. Thus, for insulating multiferroic compounds, P can be decomposed in terms of pairwise isotropic, antisymmetric, and anisotropic contributions, which can be rigorously derived in the framework of the superexchange (SE) theory, in an analogy with the spin Hamiltonian. The SE theory also allows us to identify the microscopic mechanism, which stands behind each contribution. The most controversial and intriguing one is antisymmetric or spin-current mechanism. In this work, we propose that the disputed magnetoelectric (ME) properties of Ba2CuGe2O7 can be explained solely by the spin-current mechanism, while other contributions are either small or forbidden by symmetry. First we explicitly show how the cycloidal spin order induces the experimentally observed P in the direction perpendicular to the xy plane, which can be naturally explained by the spin-current mechanism operating in the out-of-plane bonds. Then, we unveil previously overlooked ME effect, where the application of the magnetic field perpendicular to the plane not only causes the incommensurate-commensurate transition, but also flips P into the plane due to the spin-current mechanism operating in the neighboring bonds within this plane. In both cases, the magnitude and direction of P can be controlled by rotating the spin pattern in the xy plane. Our analysis is based on a realistic spin model, which was rigorously derived from the first-principles calculations and supplemented with the new algorithm for the construction of localized Wannier functions obeying the crystallographic symmetry of Ba2CuGe2O7.

arXiv comment17 pages, 8 figures

References in corpus (44)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Maximally-localized generalized Wannier functions for composite energy bands
• Wannier90: A Tool for Obtaining Maximally-Localised Wannier Functions
• Maximally localized Wannier functions: Theory and applications
• Mott Insulators in the Strong Spin-Orbit Coupling Limit: From Heisenberg to a Quantum Compass and Kitaev Models
• Maximally-localized Wannier functions for entangled energy bands
• Spin current and magneto-electric effect in non-collinear magnets
• Novel Jeff = 1/2 Mott State Induced by Relativistic Spin-Orbit Coupling in Sr2IrO4
• Ferroelectricity in spiral magnets
• Role of the Dzyaloshinskii-Moriya interaction in multiferroic perovskites
• Frequency-dependent local interactions and low-energy effective models from electronic structure calculations
• Discovery of Magnetic Antiskyrmions Beyond Room Temperature in Tetragonal Heusler Materials
• Magnetic structures and reorientation transitions in noncentrosymmetric uniaxial antiferromagnets
• Ferroelectricity induced by spin-dependent metal-ligand hybridization in Ba${}_2$CoGe${}_2$O${}_7$
• Magnetoelectric nature of skyrmions in a chiral magnetic insulator Cu2OSeO3
• Multiferroicity and skyrmions carrying electric polarization in GaV4S8
• Anisotropic Spin Hamiltonians due to Spin-Orbit and Coulomb Exchange Interactions
• Insulating Ferromagnetism in La${}_4$Ba${}_2$Cu${}_2$O${}_{10}$: an \textit{Ab Initio} Wannier Function Analysis
• General Theory for the Ferroelectric Polarization Induced by Spin-Spiral Order
• Strong Dzyaloshinskii-Moriya Interaction and Origin of Ferroelectricity in Cu2OSeO3
• Stabilization and current-induced motion of antiskyrmion in the presence of anisotropic Dzyaloshinskii-Moriya interaction
• Doppler shift picture of the Dzyaloshinskii--Moriya interaction
• Combining DFT and Many-Body Methods to Understand Correlated Materials
• Symmetry-adapted Wannier functions in the maximal localization procedure
• Full magnetoelectric response of Cr2O3 from first principles
• Field-induced Commensurate-Incommensurate phase transition in a Dzyaloshinskii-Moriya spiral antiferromagnet
• Magnetic anisotropy and low-energy spin waves in the Dzyaloshinskii-Moriya spiral magnet Ba_2 Cu Ge_2 O_7
• Equilibrium spin currents and magnetoelectric effect in magnetic nanostructures
• Mechanisms and origins of half-metallic ferromagnetism in CrO2
• Mechanism of basal-plane antiferromagnetism in the spin-orbit driven iridate Ba2IrO4
• Field-induced incommensurate-to-commensurate transition in Ba_2CuGe_2O_7
• Selectively Localized Wannier Functions
• Phase Diagram of the Dzyaloshinskii-Moriya Helimagnet Ba2CuGe2O7 in Canted Magnetic Fields
• Validity and limitations of the superexchange model for the magnetic properties of Sr2IrO4 and Ba2IrO4 mediated by the strong spin-orbit coupling
• Spin-orbit coupling and magnetic interactions in Si(111):{C,Si,Sn,Pb}
• Microscopic theory of electric polarization induced by skyrmionic order in GaV${}_4$S${}_8$
• Self-consistent linear response for the spin-orbit interaction related properties
• Spin dependence of ferroelectric polarization in the double exchange model for manganites
• Microwave Magneto-Chiral Effect in a Noncentro-symmetric Magnet CuB2O4
• Field induced phase transitions in the helimagnet Ba2CuGe2O7
• Realization of anisotropic compass model on the diamond lattice of Cu${}^{2+}$ in CuAl${}_2$O${}_4$
• Magnetization induced local electric dipoles and multiferroic properties of Ba2CoGe2O7
• Skyrmionic order and magnetically induced polarization change in lacunar spinel compounds GaV${}_4$S${}_8$ and GaMo${}_4$S${}_8$: comparative theoretical study
• Superexchange theory of electronic polarization driven by relativistic spin-orbit interaction at the half-filling

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