Influence of nonmagnetic Ga ions on the magnetoelectric coupling in CuFe_1−x Ga _x O₂

Abstract

The magnetic properties and dielectric polarization of CuFe1−xGaxO2 with various nonmagnetic Ga3+ doping levels have been measured in a wide magnetic field region, in which the observed experiment results have been explained by the consequence of the change in exchange interaction, dilution effect, and partial reduction of spin frustration. Compared with pure CuFeO2, doped nonmagnetic Ga3+ ions have an important effect on magnetization and polarization behavior and lead to an enhanced magnetoelectric coupling, especially, an enhanced spontaneous polarization has been observed in the doping amount of 0.02 and 0.05. This magnetoelectric effect appears mainly in the ferroelectric incommensurate magnetic phase region due to the noncollinear magnetic structure with a proper helical order in the CuFeO2. Based on the magnetization and polarization data, a magnetic phase diagram of temperature, magnetic field, and the doping amount are obtained.

Effect of Mn doping on the microstructure and magnetic properties of CuFeO2 ceramics

“…Although in-depth research has been conducted, the magnetic mechanism of CFOs remains elusive [3,5]. As reported in many studies, chemical substitution is an effective method for modifying the crystal structure, exchanging interactions between spins, and affecting the magnetic properties of CFO [6][7][8][9]. Elkhoun et al [10] found that www.springer.com/journal/40145 the partial replacement of Fe 3+ with Sc 3+ induced spin dilution and anti-ferromagnetic phase transition in CFO systems, causing a dimensional crossover of low-energy anti-ferromagnetic excitation from three-dimensional (3D) to two-dimensional (2D) anti-ferromagnetic interactions.…”

Regulation of Cr3+ doping on the defect characteristics and magnetic order in the CuFe1-xCrxO2 ceramics

“…In the case of CuFeO 2 , two successive antiferromagnetic transitions are observed in zero-field according to the previous powder neutron diffraction [15]. As the temperature increases in zero-field, Fe 3+ ions order in an Ising-like four-sublattice (4SL, ↑↑↓↓) configuration below T N2 ~ 11 K, then transform into the paramagnetic (PM) state above T N1 ~ 15 K through a sinusoidal amplitude-modulated quasi-long range antiferromagnetic spin structure [6,[15][16][17][18][19]. It is universally acknowledged that a slight perturbation such as the external magnetic field or foreign ions can obviously change the magnetic structure because of the unique frustrated structure.…”

“…And remarkably, this FEIC phase can be mimicked by substituting a fraction of nonmagnetic cations in the Fe sites without applied magnetic field in the recent literature[17,19,[23][24][25]. These foreign ions (S = 0), such as Al 3+ , Ga 3+ and Rh 3 + , are very efficient at converting the ground state from 4SL ↑↑↓↓ into FEIC phase.…”

Unusual magnetic behavior of TiO2-doped CuFeO2 crystals (CuFe1−xTixO2) grown by the optical floating zone method

“…[1][2][3][4] As a multiferroic material with a spin-disoriented structure, CuFeO 2 has a relatively high magnetoelectric effect. 5,6 It belongs to the R3 ¯m space group, and has a layer structure, in which Cu + ions are located between sheets of edge-shared FeO 6 octahedra. [7][8][9] Fe 3+ ions are in the high spin state with five 3d orbitals each singly occupied, and have large magnetic moments.…”