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Magnetic and Magnetotransport Studies in Transition Metal Oxides : Role of Competing Interactions

Electronic Theses of Indian Institute of Science

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Field Value
 
Title Magnetic and Magnetotransport Studies in Transition Metal Oxides : Role of Competing Interactions
 
Creator Sow, Chanchal
 
Subject Transition Metal Oxides
Condensed Matter Physics
Magnetism
Superconductivity
Transition Metal Oxides - Magnetic Properties
Transition Metal Oxides - Magneto-transport Properties
Ferromagnetism
Superconductor/Ferromagnet Heterostructures
SRO Thin Films
Superconductor/Ferromagnet Bilayers
SrRuO3 Thin Films
LixNi(2-x)O2
Physics
 
Description There was a fame time for silicon in condensed matter physics, then the graphene era came and now topological insulators are gaining lot of attention, but magnetism in condensed matter physics has remained always fascinating starting from the ancient days up to now and it will remain as one of the core topic in basic or applied physics. The improvement in the modern techniques allows one to explore magnetism in different length scales as well as in different time scales. As an effect of the improvement in experimental techniques, different magnetic anomalies are unearthed. As a result theories are getting refined and the area of magnetism progresses. From the material point of view, oxides carry the most diverse nature in condensed matter starting from high temperature superconductivity (HTS), colossal magnetoresistance, metal insulator transition etc. to ferromagnetism (FM), anti-ferromagnetism (AFM), spin glass (SG) and so on. Among this list, SG and HTS are one of the least understood topics in magnetism till today. A large research community is involved in understanding the underlying physics behind these two, especially in transition metal oxides. It has drawn attention not only due to fundamental aspects but also due to various applications in day to day life. This thesis is an attempt to understand these two phenomena in transition metal oxides.
As the title of this thesis suggest, it is all about magnetic and magneto-transport properties of certain transition metal oxide (crystalline) addressing the interplay between two competing order parameters to understand the underlying physics behind it from an experimental point of view. We have studied two different kinds of competing interactions: (i) the FM/AFM interplay either in bulk or at the interface of the two layers in thin films; (ii) the interplay between FM and superconductivity (SC) in superconductor (S)/ferromagnet (F) heterostructures. Basically both of these two kinds lead to non-equilibrium phenomena in these oxides. One of such competition is between FM and AFM leading to slow dynamics (glassy physics). Disorder and frustrations are the key ingredients for such slow dynamics. The spin frustration arises either due to geometry or due to competing interactions. For example, in a triangular antiferromagnet due to the triangular geometry spins gets frustrated. Now, if it prevails spin disorder as well then it satisfies both the criteria for a spin glass and hence it gives birth to glassiness. Another kind of competition is the interplay among SC and FM. It is known that SC and FM are two antagonistic quantum phenomena thus in a single material SC (singlet pairing) and FM does not co-exist. However one can realize this by making F/S heterostructures and observe the battle between these two competing order parameters. The spin polarized quasiparticle injection from F creates non equilibrium spin density inside S and thereby suppressing the order parameter of S. Also by choosing an appropriate ferromagnet the vortex motion inside S can be arrested to certain extent which can enhance the critical current density of S. Thus FM/SC interplay has become an alternative way to look at the high temperature superconductivity.
This thesis is categorized into nine chapters. The summary of each chapter is as follows:
Chapter: 1 contains certain concepts of magnetism and superconductivity which is useful to understand the topics and experiments described in this thesis.
Chapter: 2 gives the underlying principles of the various experimental techniques used in this thesis.
Chapter: 3 describes the magnetic properties of successfully synthesized five compositions of LixNi(2-x)O2 (0.67
 
Contributor Anil Kumar, P S
 
Date 2018-04-12T15:54:47Z
2018-04-12T15:54:47Z
2018-04-12
2013
 
Type Thesis
 
Identifier http://etd.iisc.ernet.in/2005/3398
http://etd.iisc.ernet.in/abstracts/4264/G25861-Abs.pdf
 
Language en_US
 
Relation G25861