Strain-Induced Extrinsic High-Temperature Ferromagnetism in the Fe-Doped Hexagonal Barium Titanate

Abstract

Diluted magnetic semiconductors possessing intrinsic static magnetism at high temperatures represent a promising class of multifunctional materials with high application potential in spintronics and magneto-optics. In the hexagonal Fe-doped diluted magnetic oxide, 6H-BaTiO3-δ, room-temperature ferromagnetism has been previously reported. Ferromagnetism is broadly accepted as an intrinsic property of this material, despite its unusual dependence on doping concentration and processing conditions. However, the here reported combination of bulk magnetization and complementary in-depth local-probe electron spin resonance and muon spin relaxation measurements, challenges this conjecture. While a ferromagnetic transition occurs around 700 K, it does so only in additionally annealed samples and is accompanied by an extremely small average value of the ordered magnetic moment. Furthermore, several additional magnetic instabilities are detected at lower temperatures. These coincide with electronic instabilities of the Fe-doped 3C-BaTiO3-δ pseudocubic polymorph. Moreover, the distribution of iron dopants with frozen magnetic moments is found to be non-uniform. Our results demonstrate that the intricate static magnetism of the hexagonal phase is not intrinsic, but rather stems from sparse strain-induced pseudocubic regions. We point out the vital role of internal strain in establishing defect ferromagnetism in systems with competing structural phases.

Quantum magnetism in minerals

“…Quantum Magnetism in Minerals 63 [539,540] relieves the remaining frustration through the monoclinic-to-triclinic transition. Damay et al [537] therefore argued that the magnetism in CuMnO 2 , with largely different exchange interactions on the sides of isosceles triangles, is better considered in the framework of a frustrated square-lattice model with a nearest-neighbour coupling J 1 and a diagonal interaction J 2 .…”

Double‐Exchange Magnetic Interactions in High‐Temperature Ferromagnetic Iron Chalcogenide Monolayers

“…Hence, 2D Smythite can be a good candidate for room temperature magnetic applications . To understand the nature or type of magnetic interaction, we have applied a common strategy by applying mechanical strain to observe the changes in exchange energy . However, due to the complexity of the structure, we have applied up to lattice strain to observe the effect of magnetic interaction operating in the lattice (Table ).…”

Influence of Biofield Treatment on Physical and Structural Characteristics of Barium Oxide and Zinc Sulfide

“…The reduction in volume of unit cell and increase in density suggest that BaO lattice was contracted after biofield treatment. It is previously reported that internal strain in ceramics can be produced through high temperature, doping, and milling [33,34]. In addition, it is also reported that some material respond to electric and magnetic field in form of strain such as piezoelectric material [35].…”

“…X-ray diffraction study XRD 33.25°, 47.77°, and 56.50° in T4. Furthermore, the various parameters of unit cell of BaO and ZnS were computed using PowderX software using above XRD peaks, which are presented in Table 1.…”