Abstract
Electric fields can transform materials with respect to their structure and properties, enabling various applications ranging from batteries to spintronics. Recently electrolytic gating, which can generate large electric fields and voltage-driven ion transfer, has been identified as a powerful means to achieve electric-field-controlled phase transformations. The class of transition metal oxides provide many potential candidates that present a strong response under electrolytic gating. However, very few show a reversible structural transformation at room-temperature. Here, we report the realization of a digitally synthesized transition metal oxide that shows a reversible, electric-field-controlled transformation between distinct crystalline phases at room-temperature. In superlattices comprised of alternating one-unit-cell of SrIrO3 and La0.2Sr0.8MnO3, we find a reversible phase transformation with a 7% lattice change and dramatic modulation in chemical, electronic, magnetic and optical properties, mediated by the reversible transfer of oxygen and hydrogen ions. Strikingly, this phase transformation is absent in the constituent oxides, solid solutions and larger period superlattices. Our findings open up this class of materials for voltage-controlled functionality.
Highlights
Electric fields can transform materials with respect to their structure and properties, enabling various applications ranging from batteries to spintronics
Recent advances have shown that electrolytic gating can lead to the transfer of oxygen and hydrogen ions that modifies the structure of transition metal oxides (TMOs), leading to more dramatic modulation of their physical properties[6,7]
Using in situ X-ray diffraction (XRD), we find that electrolytic gating induces a reversible structural transformation in superlattices comprised of alternating one-unit-cell of La0.2Sr0.8MnO3 and SrIrO3
Summary
Electric fields can transform materials with respect to their structure and properties, enabling various applications ranging from batteries to spintronics. Recent advances have shown that electrolytic gating can lead to the transfer of oxygen and hydrogen ions that modifies the structure of transition metal oxides (TMOs), leading to more dramatic modulation of their physical properties[6,7] To fully exploit this mechanism, materials that can be electrically switched from one crystalline phase to another, with distinct physical properties, are highly desirable. Ion transfer has been reported in many single-phase TMOs8–18, reversible, electric-field-controlled transformation between distinct crystalline phases at room-temperature (RT) has been limited to a few systems, including binary oxides VO28 and WO312,13, and perovskite oxides SrCoO3-δ14 and SrFeO3-δ17 that exhibit topotactic transformations Among these systems, coupled electronic, magnetic, and optical phase transitions have only been demonstrated in SrCoO3-δ far[14]. Together these results demonstrate the discovery of a class of oxides that exhibits reversible and coupled phase transformations with rich functionalities through electrolyte-based ionic control
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