Large Magnetovolume Effect Induced by Embedding Ferromagnetic Clusters into Antiferromagnetic Matrix of Cobaltite Perovskite

Abstract

Materials that show negative thermal expansion (NTE) have significant industrial merit because they can be used to fabricate composites whose dimensions remain invariant upon heating. In some materials, NTE is concomitant with the spontaneous magnetization due to the magnetovolume effect (MVE). Here the authors report a new class of MVE material; namely, a layered perovskite PrBaCo O (0 ≤ x ≤ 0.41), in which strong NTE [β ≈ -3.6 × 10 K (90-110 K) at x = 0.24] is triggered by embedding ferromagnetic (F) clusters into the antiferromagnetic (AF) matrix. The strongest MVE is found near the boundary between F and AF phases in the phase diagram, indicating the essential role of competition between the F-clusters and the AF-matrix. Furthermore, the MVE is not limited to the PrBaCo O but is also observed in the NdBaCo O . The present study provides a new approach to obtaining MVE and offers a path to the design of NTE materials.

Room Temperature Zero Thermal Expansion in a Cubic Cobaltite

“…We have also unveiled with compelling evidence the underlying mechanism of the ATE in La 0.5 Ba 0.5 CoO 3– x is the phase conversion between AF-LVP and F-SVP. The mechanism is consistent with what we have found in the A-site ordered perovskite with orthorhombic crystal structure, PrBaCo 2 O 5.5+ x , − so that we believe the scenario of AF-LVP–F-SVP transition is ubiquitous in the family of cobaltite perovskite, regardless of A-site ions and its ordering.…”

Electron doping induced magnetic glassy state in phase separated YBaCo2O5.5-δ

“…Additionally, the magnetic and transport measurements showed the formation of two insulating phases for the electron-doped region (δ < 0.45), whereas the hole-doped region (δ > 0.45) showed the coexistence of insulating and metallic phases. More importantly, Miao et al studies on hole doped PrBaCo2O5.5+δ (δ = 0.24) showed a large magnetovolume effect, which is due to the inserting of ferromagnetic clusters into the antiferromagnetic matrix [5]. The δ ≈ 0.5 cobaltites exhibit a Co 3+ high spin (HS; t 2g 4 e g 2 , S=2)intermediate spin (IS; 2 5 1 , S=1) and IS -low spin (LS, t 2g 6 e g 0 , S = 0) state transitions phases [1], [21], whereas both electron and hole doped cobaltites show melting of spin-state ordering [22].…”

“…Layered cobaltites RBaCo2O5+δ (R = lanthanide ion or Y and δ ~ 0.5) have been intensively studied over the years due to unusual structural, magnetic and electronic phase transitions [1], [2], [3], [4], [5], [6], [7], [8], [9], [10].…”

Low temperature magnetic behavior and thermal expansion anomaly of cubic CeTiO3

“…9 ). 33 It is noticed that the distinct MVE is observed below 300 K and increases gradually upon cooling. The MVE provides a positive contribution on lattice parameters.…”