Versatile Magneto-Dielectric Response of Epitaxial Thin Films of the High Entropy Oxide Perovskite Nd(Cr<sub>0.2</sub>Mn<sub>0.2</sub>Fe<sub>0.2</sub>Co<sub>0.2</sub>Ni<sub>0.2</sub>)O<sub>3</sub>.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41937197.
- Also identified by DOI 10.1002/adma.72992 and PMC identifier 13155305.
- Licence recorded as CC BY.
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Abstract
We report the dielectric and magnetic properties of epitaxial thin films of the high entropy oxide (HEO) perovskite Nd(Cr<sub>0.2</sub>Mn<sub>0.2</sub>Fe<sub>0.2</sub>Co<sub>0.2</sub>Ni<sub>0.2</sub>)O<sub>3,</sub> which orders magnetically below T<sub>mag</sub>≈190 K. At T ≫ T<sub>mag</sub>, the dielectric response reveals a Debye-type frequency dependence with a zero-frequency dielectric constant of <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics> <msub><msup><mi>ε</mi> <mo>'</mo></msup> <mi>r</mi></msub> <annotation>${{\varepsilon ^{\prime}}_r}$</annotation></semantics> </math> ≈230-250. The dc bias voltage loops of <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics> <msub><msup><mi>ε</mi> <mo>'</mo></msup> <mi>r</mi></msub> <annotation>${{\varepsilon ^{\prime}}_r}$</annotation></semantics> </math> are reversible but exhibit three distinct peaks centred at zero and finite positive and negative voltage. We provide evidence that the zero-bias peak is governed by the oxygen sublattice while the finite bias peaks originate from cationic dipoles. The maximal response of the latter appears to be shifted to finite bias by a static uncompensated electric field due to a vertical gradient of the oxygen content. Below T<sub>mag</sub>, this anomalous dielectric response is strongly suppressed, presumably by magnetostriction that counteracts and freezes the ionic displacements. These findings indicate a unique correlation between configurational entropy, dielectric response, and magnetic properties. In combination with a large dielectric strength, it enables a non-hysteretic tuning of the dielectric response of magnetoelectronic devices with multiple parameters like temperature, electric, and magnetic field. This HEO is equally interesting for fundamental studies of competing electric and magnetic orders in strongly disordered materials.