Antisite Defects and Chemical Expansion in Low‐damping, High‐magnetization Yttrium Iron Garnet Films

Santiso, José; García, Carlos; Romanque, Cristian; Henry, Loïc; Bernier, Nicolas; Bagués, Núria; Caicedo, José Manuel; Valvidares, Manuel; Sandiumenge, F.

doi:10.1002/cnma.202200495

Cited by 1 publication

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“…[ 7–12 ] Such point defects can be present in much higher concentrations in thin films compared to bulk, due to epitaxial stabilization of a crystal structure with a composition deviating from bulk. [ 11,12 ]…”

Section: Introductionmentioning

confidence: 99%

“…[ 6 ] The electrical, magnetic, optical, and transport properties of these and other complex oxides are strongly influenced by point defects resulting from a nonideal cation stoichiometry. [ 7–12 ] Such point defects can be present in much higher concentrations in thin films compared to bulk, due to epitaxial stabilization of a crystal structure with a composition deviating from bulk. [ 11,12 ]…”

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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Composition‐Dependent Ferroelectricity of LuFeO₃ Orthoferrite Thin Films

Cho

Klyukin

et al. 2023

Adv Elect Materials

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oxides are strongly influenced by point defects resulting from a nonideal cation stoichiometry. [7][8][9][10][11][12] Such point defects can be present in much higher concentrations in thin films compared to bulk, due to epitaxial stabilization of a crystal structure with a composition deviating from bulk. [11,12] The orthoferrites (RFeO 3 ) are perovskite-derived structures in which tilting of the Fe octahedra yields an orthorhombic lattice with four formula units (f.u.) per unit cell. [13] Fe 3+ cations are coupled antiferromagnetically with Néel temperature T N ≈ 640 K. The Dzyaloshinskii-Moriya interaction (DMI) between neighboring Fe 3+ leads to a small canting angle and a net moment ≈0.05 µ B per f.u. at room temperature. The antiferromagnetic configuration of Fe 3+ (Γ 1 , Γ 2 , or Γ 4 in Bertaut notation) and the magnetic transition temperatures between different antiferromagnetic states varies with the rare earth. For a nonmagnetic R 3+ such as Lu 3+ , the configuration remains Γ 4 (G x A y F z , i.e., G-type antiferromagnet with spins oriented along x, with secondary A-type antiferromagnetic arrangement along y, and a net moment along z) from 0 K up to T N . [14,15] Some orthoferrites can exhibit multiferroicity at cryogenic temperatures when R 3+ ions are magnetically ordered. [16] The mechanism for such ferroelectricity is the exchange interaction between R 3+ and Fe 3+ , which leads to ionic displacement, breaks the symmetry, and thus leads to polarization on the order of 0.1 µC cm −2 . [16,17] Introducing room-temperature ferroelectricity into antiferromagnetic orthoferrites is an appealing strategy to expand the range of room temperature multiferroic materials. The most widely studied multiferroic is BiFeO 3 (BFO), which is a rhombohedral or tetragonal structure. Its ferroelectricity is derived primarily from the Bi 3+ lone pairs and exhibits a high ferroelectric Curie temperature (T C = 1103 K). [18] As in the rare earth orthoferrites, the magnetism in BFO arises from the canting of antiferromagnetically ordered Fe 3+ spins with T N = 643 K. Rare earth orthoferrites lack the lone pairs of BFO, and the centrosymmetric orthorhombic space group (Pbnm) prohibits ferroelectricity. However, Y Fe antisite defects in Y-rich yttrium orthoferrite YFeO 3 (YFO) thin films bring about a noncentrosymmetric structural distortion and induce ferroelectric polarization of ≈10 µC cm −2 at room temperature. [19][20][21] According to first principles calculations, such an antisite defect mechanism is expected to be applicable in other rare earth rich orthoferrites, with the polarization increasing with decreasing ionic radius of R 3+ ; LuFeO 3 (LFO) lies at the higher end of This work characterizes the structural, magnetic, and ferroelectric properties of epitaxial LuFeO 3 orthoferrite thin films with different Lu/Fe ratios. LuFeO 3 thin films are grown by pulsed laser deposition on SrTiO 3 substrates with Lu/Fe ratio ranging from 0.6 to 1.5. LuFeO 3 is antiferromagnetic with a weak canted moment perpendicular to the f...

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Section: Introductionmentioning

confidence: 99%