Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


Thesis.pdf (2.88 MB)

ETD Abstract Container

Abstract Header

Spin-Orbital Order and Condensation in 4d and 5d Transition Metal Oxides

Svoboda, Christopher
http://rave.ohiolink.edu/etdc/view?acc_num=osu1500397435319782

Abstract Details

2017, Doctor of Philosophy, Ohio State University, Physics.
Strong correlations and strong spin-orbit coupling are important areas of research in condensed matter physics with many open questions. Transition metal oxides provide a natural way to combine these strong correlations and strong spin-orbit coupling in electronic systems. Iridium compounds in the d5 configuration (Ir4+) have received most of the focus in this area for the last decade, yet there remains much more unexplored territory with other electron counts. Here we explore the magnetism in several classes of 4d and 5d Mott insulating transition metal oxides with d1, d2, and d4 electron counts. We first cover double perovskites A2BB'O6 where the B' ion is in either the d1 and d2 configuration and the other ions are nonmagnetic. We develop and solve magnetic models with both spin and orbital degrees of freedom within mean field theory. The anisotropic orbital degrees of freedom play a crucial role in resolving some outstanding puzzles in these compounds including why ferromagnetism is common in d1 but not d2 and why the d1 ferromagnets have negative Curie-Weiss temperatures. Then we cover a broad class of compounds in the d4 configuration. Despite the fact that Hund's rules dictate the ground state should be nonmagnetic, we find that superexchange may induce magnetic moments and magnetic ordering through the condensation of triplon excitations. We find condensation occurs only at k = π which generates antiferromagnetic order in the models we consider, and strong Hund's coupling does not induce ferromagnetism in the large spin-orbit coupling limit even though it induces ferromagnetic interactions in the absence of spin-orbit coupling. We then apply our results to the d4 double perovskite Ba2YIrO6. Although experimental observations indicate the material possesses magnetic moments, we show that these magnetic moments are likely not due to condensation induced by superexchange.
Nandini Trivedi (Advisor)
Mohit Randeria (Committee Member)
Jay Gupta (Committee Member)
Linda Carpenter (Committee Member)
123 p.
Physics
magnetism; Mott insulators; spin-orbit coupling

Recommended Citations

Citations

  • Svoboda, C. (2017). Spin-Orbital Order and Condensation in 4d and 5d Transition Metal Oxides [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500397435319782

    APA Style (7th edition)

  • Svoboda, Christopher. Spin-Orbital Order and Condensation in 4d and 5d Transition Metal Oxides. 2017. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1500397435319782.

    MLA Style (8th edition)

  • Svoboda, Christopher. "Spin-Orbital Order and Condensation in 4d and 5d Transition Metal Oxides." Doctoral dissertation, Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500397435319782

    Chicago Manual of Style (17th edition)

osu1500397435319782
3,246
© 2017, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.