ABSTRACT High entropy oxides hold the potential to revolutionize the conventional material paradigms by leveraging high order of chemical disorder that induces highly desirable exotic phases for advanced applications. Combined with epitaxial strain, we show that high entropy can further manipulate the phase of these locally disordered materials. Using time‐averaged and time resolved Terahertz (THz) spectroscopy as dynamic probe, for the first time we show a rare combination of i) crystal axis dependent insulator to metal THz electronic phase transition and ii) coexistence of negative and positive THz photoconductivity at room temperature. Detailed analysis within theoretical models, including density functional theory‐based band structure calculations, suggest origin of these properties as disproportionate ordering of oxygen vacancies. This work underlines the pivotal role of high entropy oxides in advancing diverse THz functionalities, representing a critical step toward futuristic applications like THz‐based high‐speed communication and computation with an emphasis in THz frequency domain.
Kumar et al. (Wed,) studied this question.