Diracovi polumetali s magnetskim uređenjem Eu atoma

master's thesis

• Title (english): Dirac semimetals with magnetically ordered Eu atoms
• Author: Luka Akšamović
• Mentor: Mario Novak (mentor)
• Committee member: Mario Novak (predsjednik povjerenstva)
• Committee member: Danko Radić (član povjerenstva)
• Committee member: Mihael Srđan Grbić (član povjerenstva)
• Committee member: Zoran Rukelj (član povjerenstva)
• Committee member: Miroslav Požek (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; Zagreb
• Defense date and country: 2022-10-27, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract

Diracova materija grupno je ime za materijale u kojima se javljaju pobuđenja koja se mogu prikladno opisati Diracovom jednadžbom. U tu klasu materijala spadaju grafen, topološki izolatori, 3D Diracovi polumetali, Weylovi polumetali te ostali. U ovom diplomskom radu proučavana su svojstva tri materijala: EuCd2As2, EuCd2Pb2 te EuCd2P2 za koje se smatra da pripadaju klasi Diracovih materijala. Sva tri navedena spoja su izostrukturalna i po mnogim svojstvima slična. U kontekstu Diracove materije posebno su zanimljiva magnetska svojstva ovih triju materijala koja dolaze od uređenja europijevih atoma. U nastavku rada bit će detaljno opisan proces sinteze monokristala triju navedenih materijala. Na sintetiziranim uzorcima napravljena je rendgenska difrakcija na prahu čime je potvrđena željena struktura dobivenih kristala. Pomoću Laueove difrakcije određene su orijentacije kristalnih osi za dobivene
uzorke, dok je pomoću rendgenske fluorescentne spektroskopije određen atomski udio elemenata u kristalima. Poznavanje orijentacije kristala omogućilo je mjerenje transportnih svojstava materijala duž određenih kristalnih osi. Pomoću niskotemperaturnog mjernog postava izmjerena je ovisnost otpornosti materijala o temperaturi u rasponu od sobne temperature do 2 K, ovisnost otpornosti materijala o magnetskom polju te Hallov koeficijent.

Abstract (english)

A group of materials that experience excitations which can be described by the Dirac equation are referred to as the Dirac matter. Graphene, topological insulators, 3D Dirac semimetals, Weyl semimetals, and many others belong to this group. Here, we study the properties of these three compounds; EuCd2As2, EuCd2Pb2, and EuCd2P2. According to the previously published measurements, these are considered to be Dirac materials. All three compounds are isostructural and mutually similar by many different properties. The most interesting, in the context of the Dirac matter, are their magnetic properties, originating from the arrangement of europium atoms. In this
work, we explain the synthesis of single crystals of the three compounds in detail. We present the results of testing the structure of the synthesized single crystals by performing the X-ray diffraction method on powder samples. Using the Laue diffraction method, we find the orientations of the crystal axes for the synthesized single crystals, and using the X-ray fluorescence spectroscopy we determine their elemental compositions. Furthermore, utilizing the obtained information on the orientation, we measure the transport properties of single crystals of the three materials along
the a priori determined crystal axes. We use a low-temperature measurement setup to test how the electrical resistance depends on the temperature, magnetic field and we find the corresponding Hall coefficients.

• Keywords: magnetski Diracovi sustavi; magnetsko uređenje; sinteza monokristala; magnetotransportna svojstva
• Keywords (english): magnetic Dirac systems; magnetic order; single crystal synthesis; magnetotransport properties
• Language: croatian
• URN:NBN: urn:nbn:hr:217:501860
• Study programme: Title: The University Integrated Undergraduate and Graduate Programme in Physics; Research Physics; specializations in: Research Physics; Course: Research Physics; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: sveučilišni magistar fizike (sveučilišni magistar fizike)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access; Embargo expiration date: 2023-10-27
• Created on: 2024-02-06 09:01:12