Magnetska dinamika dvoslojnog manganita La1.4Sr1.6Mn2O7

master's thesis

• Title (english): Magnetic dynamics of bilayer manganite La1.4Sr1.6Mn2O7
• Author: Veronika Sunko
• Mentor: Ivica Živković (mentor)
• Mentor: Damir Pajić (mentor)
• Committee member: Damir Pajić (predsjednik povjerenstva)
• Committee member: Ivica Živković (član povjerenstva)
• Committee member: Ivan Kupčić (član povjerenstva)
• Committee member: Miroslav Požek (član povjerenstva)
• Committee member: Hrvoje Buljan (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2014-09-24, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract

U ovom radu je istraživana magnetska dinamika dvoslojnog manganita La1.4Sr1.6Mn2O7 mjerenjem linearne i nelinearne izmjenične susceptibilnosti na temperaturama izmedu 4.2 K i 400 K, te magnetizacije izmedu 320 K i 500 K. Dokazano je postojanje Griffithsove faze na 370 K, dugodosežnog magnetskog uređenja na 91.2 K, te pojava staklastog ponašanja na temperaturama nižima od uređenja, s temperaturom ostakljivanja od 26.4 K. Također, uočeno je pet feromagnetskih prijelaza između 250 K i 320 K, koje pripisujemo kristalnim defektima. Predložen je model prema kojem su defekti zaslužni za metalnu vodljivost duž c kristalnog smjera na temperaturama ispod magnetskog uređenja.

Abstract (english)

The magnetic dynamics of the bilayer manganite La1.4Sr1.6Mn2O7 was investigated by measuring the linear and nonlinear AC susceptibility between 4.2 K and 400 K, and magnetization between 320 K and 500 K. It was proven that a Griffiths-like phase appears at 370 K, and that long range order is set at 91.2 K. Bellow the ordering temperature the system behaves as a reentrant spin glass, with the freezing temperature of 26.4 K. Also, there are five ferromagnetic transitions between 250 K and 320 K, which are attributed to crystal defects. We propose a model according to which these defects cause the metallic conduction in the c crystallographic direction in the magnetically ordered phase.

• Keywords: Magnetska dinamika dvoslojnog manganita La1.4Sr1.6Mn2O7; magnetska dinamika
• Language: croatian
• URN:NBN: urn:nbn:hr:217:119696
• Study programme: Title: Physics; specializations in: Research; Course: Research; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: magistar/magistra fizike (magistar/magistra fizike)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-06-16 11:55:36