Magnetotransport properties of selected high entropy alloys

doctoral thesis

• Title (croatian): Magnetotransportna svojstva odabranih visokoentropijskih slitina
• Author: Marko Kuveždić
• Mentor: Mario Basletić (mentor)
• Committee member: Danko Radić (predsjednik povjerenstva)
• Committee member: Mario Basletić (član povjerenstva)
• Committee member: Tomislav Ivek (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2023-10-06, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics
• Universal decimal classification (UDC): 53 - Physics

Abstract

This thesis presents the findings of a comprehensive, systematic study of transport properties, including resistivity, Hall effect, magnetoresistance, and superconductivity, in amorphous quinary alloys of early and late transition metals. The research focused on metallic glass ribbons from three alloy systems: (TiZrNbNi)1−xCux, (TiZrNbCu)1−xNix, and (TiZrNbCu)1−xCox, spanning a broad composition range, along with three alloy variants with a fixed TL (Cu, Ni) content and compositions: Ti0.30Zr0.15Nb0.15Ni0.20Cu0.20, Ti0.15Zr0.30Nb0.15Ni0.20Cu0.20, and Ti0.15Zr0.15Nb0.30Ni0.20Cu0.20. In addition, measurements were conducted on an amorphous thin film of TiZrNbCuNi, which was deposited on a SrLaAlO4 substrate using a pulsed laser deposition (PLD) system. The results of resistivity, Hall effect, magnetoresistance, and superconductivity measurements largely agree with those reported in previous investigations on related binary and ternary amorphous alloys. However, we identified a novel model of two parallel conducting channels, composed of a metal-like and a variable range hopping (VRH)-like channel, that better describes the temperature variation of resistivity observed in our experiments. A possible mechanism for the origin of these two conductance channels was proposed.

Abstract (croatian)

Materijali s kristalnim uređenjem uvijek su privlačili veliki interes znanstvene zajednice, posebno od razvoja kvantne mehanike. Međutim, savršene kristalne strukture su češće iznimka nego pravilo u prirodi. Umjesto toga, strukture u materijalima variraju od kristalnih rešetci s malim brojem defekata, do vrlo neuređenih amorfnih (staklastih) struktura. Amorfni metali su čisti metali ili legure koje ne posjeduju dugodosežno atomsko uređenje, a nastaju raznim tehnikama brzog hlađenja taljevine ili plina. Brzina procesa sprječava stvaranje uređene kristalne faze pa atomi ostaju „smrznuti” u metastabilnom stanju koje nalikuje tekućoj fazi. Razvoj tehnika brzog hlađenja tijekom 1960-ih doveo je do povećanog interesa za amorfna metalna stakla i utjecaja dugodosežnog (ne)uređenja na elektronsku strukturu, mehanička, magnetska i električna svojstva metala. Među metalnim staklima, od posebnog su značaja slitine ranih (Ti, Zr, Nb, Hf) i kasnih (Fe, Co, Ni, Cu) prijelaznih metala, poznate skraćeno kao TE–TL slitine. Ove slitine su od posebnog interesa zbog širokog raspona koncentracija (obično između 20% i 70% sadržaja kasnih prijelaznih metala) za koje je moguće formirati metalno staklo. Ovo svojstvo omogućuje detaljno i sustavno proučavanje ovisnosti svojstava materijala o kemijskom sastavu, jer je kod amorfnih slitina, za razliku od kristalnih, moguće dobiti homogenu jednofaznu smjesu s kontinuiranim vrijednostima kemijskog sastava.

• Keywords: amorphous alloys; metallic glasses; amorphous thin films; pulsed laser deposition; transport properties; resistivity; Hall effect; magnetoresistance; superconductivity; weak localization; enhanced electron-electron interactions; Anderson localization; variable range hopping
• Keywords (croatian): amorfne slitine; metalna stakla; amorfni tanki filmovi; pulsna laserska depozicija; transportna svojstva; otpornost; Hallov efekt; magnetootpor; supravodljivost; slaba lokalizacija; pojačane elektron-elektron interakcije; Andersonova lokalizacija; preskakanje promjenjivog dosega
• Language: english
• URN:NBN: urn:nbn:hr:217:537445
• Promotion: 2023
• Project: Number: IP-2018-01-7828; Title: Sulfasoli: nova generacija kompleksnih funkcionalnih materijala; Title: Sulfosalts: new generation of complex fuctional materials; Acronym: SulfNewFunMat; Leader: Denis Sunko; Jurisdiction: Croatia; Funder: HRZZ; Funding stream: IP
• Study programme: Title: Doctoral study; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti u području prirodnih znanosti (doktor/doktorica znanosti u području prirodnih znanosti)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-11-13 13:15:41