Exchange-bias field induced by surface inhomogeneities in ferromagnetic/charge-ordered bilayer structure

Zhang

J. Phys.: Condens. Matter

et al. 2021

Self Cite

Emergent phenomena at interfaces have been investigated intensely in pursuit of the next generation spintronics. In this work, we have integrated heterostructure consisting of paramagnetic (PM) metallic Pt and antiferromagnetic (AFM) insulator LaMnO 3 (LMO). High-quality Pt (3 nm)/LMO (100 nm) heterostructure has been obtained by pulsed laser deposition. The structure, lattice strain and magnetic properties of epitaxial Pt/LMO heterostructure are fully studied. Due to the high sensitivity of synchrotron radiation and the high quality of epitaxial layer, the reflection intensity of the 3 nm-thick ultrathin Pt layer and LMO layer can be detected, and then lattice strain can be calculated. The LMO layer is under relative large tensile strain (2.13%), while the Pt layer is under relative small compressive strain (−0.46%). Magnetization measurements suggest that unexpected ferromagnetic behavior is observed clearly in the PM-Pt/AFM-LMO heterostructure. Moreover, spin glass (SG) state and exchange bias (EB) is also observed in this heterostructure. SG state is observed as a result of competing magnetic orders and spin frustration at the Pt/LMO interface. The heterostructure shows the EB effect below blocking temperature (T B ), which is much lower than the Néel temperature (T N ) of LMO, suggesting that the EB is strongly related to the SG state. The EB originates from the coupling between the SG and AFM phases.

Section: Resultssupporting

confidence: 60%

Spin glass feature and exchange bias effect in metallic Pt/antiferromagnetic LaMnO₃ heterostructure

Zhang

J. Phys.: Condens. Matter

et al. 2021

Self Cite

“…The 7.5% sample, presented in Figure 6b, exhibited an unusual intercrossing of ZFC and FC profiles, at approximately 10 K. Past research has attributed intercrossing of ZFC and FC profiles to the competition between ferromagnetic and antiferromagnetic phases. 27,28 Consequently, one possible explanation for this result is the formation of an antiferromagnetic Li x CoSe phase. However, a second possibility is the formation of a filamentary superconducting phase.…”

Section: ■ Results and Discussionmentioning

confidence: 97%

On the Electrochemical Phase Evolution of Anti-PbO-Type CoSe in Alkali Ion Batteries

et al. 2021

The reaction mechanism of anti-PbO type CoSe in Li, Na, and K ion half cells is studied. Ex situ X-ray diffraction data is analyzed with the Rietveld method, in conjunction with discharge profiles and extended cycling data. These indicate that intercalation followed by a conversion reaction occur in all systems. For the case of Na, the intercalation reaction was associated with a contraction in the stacking axis lattice parameter, whereas Li and K exhibited expansion. Magnetic susceptibility versus temperature measurements of Li- and Na-intercalated CoSe samples produce unusual results, and several explanations are proposed, including the formation of a superconductive phase. Extended cycling experiments are also performed, and high initial capacities of 937, 657, and 972 mAh/g are observed for Li, Na, and K, respectively. However, all systems exhibit significantly lower second discharge capacities of 796, 530, and 515 mAh/g. The capacities continue to decline during extended cycling, with the systems exhibiting tenth cycle capacity fades of 52, 85, and 95% and Li half cells exhibit capacities over 150 mAh/g at 15 mA/g after 50 cycles. The capacity fade is likely attributable to volume changes and irreversibility associated with conversion and intercalation reactions. This work correlates electrochemical features to the structural evolution, magnetic properties, and reaction mechanisms.

“…Furthermore, a bifurcation between the ZFC and FC curves has been observed at an irreversibility temperature (T irr ), which is slightly higher than T B . Such bifurcation might be caused by the existence of the spin glass state and/or the non-uniformity of the magnetic phase (Wang et al, 2021;Wang et al, 2015). Then, the Curie temperature (T c ) could be determined by the M-T curves where magnetization starts to increase dramatically, which is also the magnetic phase transition temperature.…”

Section: Resultsmentioning

confidence: 99%

Flexible La0.67Sr0.33MnO3:ZnO Nanocomposite Thin Films Integrated on Mica

et al. 2022

The integration of functional oxide thin films on flexible substrates is critical for their application in flexible electronics. Here, to achieve flexible perovskite manganite oxide film with excellent low-field magnetoresistance (LFMR) effect, textured La0.67Sr0.33MnO3 (LSMO):ZnO nanocomposite film was deposited on a flexible mica substrate with ZnO buffer using pulsed laser deposition (PLD). Compared to the polycrystalline LSMO:ZnO nanocomposite film directly deposited on mica without buffer, the LSMO:ZnO/ZnO/mica sample exhibits larger saturation magnetization (164 emu/cm3) and higher Curie temperature (∼319 K), which results from the crystallinity and strain in the LSMO phase. In addition, the LSMO:ZnO/ZnO/mica film presents a high MR value of ∼39% at 10 K under 1 T. Furthermore, the good mechanical stretchability and property stability of the nanocomposite thin films have been demonstrated with mechanical bending.