A Lattice Litany for Transition Metal Oxides

Abstract

In this tribute to K Alex Müller, I describe how his early insights have influenced future decades of research on perovskite ferroelectrics and more broadly transition metal oxides (TMOs) and related quantum materials. I use his influence on my own research journey to discuss impacts in three areas: structural phase transitions, precursor structure, and quantum paraelectricity. I emphasize materials functionality in ground, metastable, and excited states arising from competitions among lattice, charge, and spin degrees of freedom, which results in highly tunable landscapes and complex networks of multiscale configurations controlling macroscopic functions. I discuss competitions between short- and long-range forces as particularly important in TMOs (and related materials classes) because of their localized and directional metal orbitals and the polarizable oxygen ions. I emphasize crucial consequences of elasticity and metal–oxygen charge transfer.

From SrTiO3 to Cuprates and Back to SrTiO3: A Way Along Alex Müller’s Scientific Career

“…Depending on the testing tool, either of both appears dominant and yields a corresponding interpretation. Note that, in the paper by Bishop in Reference [43], similar aspects and beyond are addressed, and more detailed consequences are given.…”

Correlation of strontium anharmonicity with charge-lattice dynamics of the apical oxygens and their coupling to cuprate superconductivity

“…Since the discovery of high-temperature superconductivity (HTSC) in cuprates and related materials [1], decades of intense study have revolutionized branches of condensed matter physics, but have yet to yield a consensus on the origins of the superconductivity. This has led the community to call for new ideas [2][3][4][5]. Notably in the search for a universal characteristic, two-site distributions in the dynamic structures of certain Cu-O pairs (figures 1(a) and (b)), coupled to HTSC have been observed in virtually all hole-doped cuprates via extended x-ray absorption fine structure (EXAFS) measurements that probe the instantaneous structure factor, S(Q, t = 0) [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20].…”