scholarly journals A Lattice Litany for Transition Metal Oxides

2020 ◽  
Vol 5 (3) ◽  
pp. 46
Author(s):  
Alan R. Bishop
Keyword(s):  
Phase Transitions ◽  
Transition Metal ◽  
Metal Oxides ◽  
Excited States ◽  
Transition Metal Oxides ◽  
Degrees Of Freedom ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
Oxygen Ions ◽  
Precursor Structure

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.

scholarly journals Electret formation in transition metal oxides by electrochemical amorphization

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Yong-Jin Kim ◽  
Chan-Ho Yang
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Charge Density ◽  
Electric Fields ◽  
Transition Metal Oxides ◽  
Degrees Of Freedom ◽  
Permanent Magnets ◽  
Underlying Mechanism ◽  
Diffusion Reaction ◽  
Wide Range

AbstractTransition metal oxides (TMOs) are an important class of materials that show a wide range of functionalities involving spin, charge, and lattice degrees of freedom. The strong correlation between electrons in d-orbitals and the multivalence nature give rise to a variety of exotic electronic states ranging from insulator to superconductor and cause intriguing phase competition phenomena. Despite a burst of research on the multifarious functionalities in TMOs, little attention has been paid to the formation and integration of an electret—a type of quasi-permanent electric field generator useful for nanoscale functional devices as an electric counterpart to permanent magnets. Here, we find that an electret can be created in LaMnO3 thin films by tip-induced electric fields, with a considerable surface height change, via solid-state electrochemical amorphization. The surface charge density of the formed electret area reaches ~400 nC cm−2 and persists without significant charge reduction for more than a year. The temporal evolution of the surface height, charge density, and electric potential are systematically examined by scanning probe microscopy. The underlying mechanism is theoretically analyzed based on a drift-diffusion-reaction model, suggesting that positively charged particles, which are likely protons produced by the dissociation of water, play crucial roles as trapped charges and a catalysis to trigger amorphization. Our finding opens a new horizon for multifunctional TMOs.

Preparation, Characterization, and Structural Phase Transitions in a New Family of Semiconducting Transition Metal Oxychalcogenides β-La2O2MSe2(M= Mn, Fe)

2010 ◽  
Vol 22 (22) ◽  
pp. 6171-6182 ◽  
Author(s):  
Emma E. McCabe ◽  
David G. Free ◽  
Budhika G. Mendis ◽  
Joshua S. Higgins ◽  
John S. O. Evans
Keyword(s):  
Phase Transitions ◽  
Transition Metal ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
New Family

Excited States as a Probe of Structural Phase Transitions in Polyphenyl Crystals

2002 ◽  
Vol 272 (1) ◽  
pp. 161-166 ◽  
Author(s):  
Takeshi Shigenari ◽  
Kohji Abe ◽  
Masaki Mizuno ◽  
Kenji Ishida ◽  
Toshihiro Suzuki ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Excited States ◽  
Structural Phase ◽  
Structural Phase Transitions

Synchrotron Moessbauer Spectroscopy and Resistivity Studies of Iron Oxide Under High Pressure

2006 ◽  
Vol 987 ◽  
Author(s):  
Viktor V. Struzhkin ◽  
Mikhail I. Eremets ◽  
Ivan M. Eremets ◽  
Jung-Fu Lin ◽  
Wolfgang Sturhahn ◽  
...  
Keyword(s):  
High Pressure ◽  
Magnetic Properties ◽  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
High Pressures ◽  
Structural Phase ◽  
Experimental Studies ◽  
Magnetic Interactions ◽  
Diamond Anvil

AbstractThe strong electron correlations play a crucial role in the formation of a variety of electronic and magnetic properties of the transition metal oxides. In strongly correlated electronic materials many theoretical predictions exist on pressure-induced insulator-metal transitions, which are followed by a collapse of localized magnetic moments and by structural phase transitions [1]. The high-pressure studies provide additional degree of freedom to control the structural, electronic, optical, and magnetic properties of transition metal oxides. With the development of the high-pressure diamond-anvil-cell technique the experimental studies of such transitions are now possible with the advanced synchrotron techniques. In our studies, the iron monooxide Fe0.94O was studied under high pressures up to 200 GPa in diamond anvil cells. The single crystals enriched with Fe57 isotopes have been prepared for nuclear resonance measurements. The results of synchrotron Mössbauer spectroscopy (nuclear forward scattering -NFS), and electro-resistivity measurements suggest a complicated scenario of magnetic interactions governed by band-broadening effects.

Charge and orbital ordering in transition metal oxides

2002 ◽  
Vol 12 (9) ◽  
pp. 257-257
Author(s):  
D. Khomskii
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Degrees Of Freedom ◽  
Relative Role ◽  
Strongly Correlated ◽  
Orbital Ordering ◽  
Spin Orbital ◽  
Electron Phonon Interaction ◽  
Frustrated Systems

Transition metal oxides with strongly correlated d-electrons show an astonishing variety of properties. This is largely determined by an interplay of different degrees of freedom: charge, spin, orbital, lattice ones. Often there appear in them various superstructures. In this talk I will consider different types of superstructures in transition metal oxides, especially charge and orbital ordering, willdiscuss the main mechanisms leading to their formation and consider specific examples of superstructures in manganites, cobaltites and in some frustrated systems. Relative role of purely electronic mechanisms and of the electron-phonon interaction will be discussed. In particular, I will show that the elastic interactions can naturally lead to different superstructures, including stripes. Special features of charge and, especially, orbital ordering in frustrated systems, where frustrations may be caused both by the geometric structure of the lattice and by the special features of orbital interactions, will be considered, and it will be shown that the order-from-disorder mechanism can lead to a unique ordered ground state in many of these cases..

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