Novel phases in quasi-one-dimensional frustrated spin chain LiCuSbO4

doctoral thesis

• Title (croatian): Nove faze u kvazijednodimenzionalnom frustriranom spinskom lancu LiCuSbO4
• Author: Marko Bosiočić
• Mentor: Miroslav Požek (mentor)
• Mentor: Fabrice Bert https://orcid.org/0000-0003-3627-5228 (komentor)
• Committee member: Mihael Srđan Grbić (predsjednik povjerenstva)
• Committee member: Mirta Herak (član povjerenstva)
• Committee member: Miroslav Požek (član povjerenstva)
• Committee member: Fabrice Bert https://orcid.org/0000-0003-3627-5228 (član povjerenstva)
• Committee member: Danko Radić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2022-10-07, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics
• Universal decimal classification (UDC): 53 - Physics

Abstract

Search for novel (quantum) states of matter is one of the prime goals of contemporary physics. Spin nematic phase, where spins form a state with vanishing dipolar moment while a more complex operator remains with non zero expectation value, was predicted in one dimensional (1D) spin systems with ferromagnetic (FM) interaction between first and antiferromagnetic (AFM) interaction between second neighbours in the region near saturation field. After decades of mainly theoretical work in low dimensional spin systems, the first material candidates started to emerge, albeit no clear experimental evidence for such a phase was presented so far. In this thesis, extensive experimental research on LiCuSbO_4 compound, a spin nematic candidate, is presented. This material shows distinct properties: absence of 3D ordering in zero magnetic field down to 30 mK, saturation field of ≈13 T. Nuclear magnetic resonance (NMR), muon spin rotation (μSR) and magnetic susceptibility (SQUID) techniques were used to unravel and tackle different parts of the experimental phase diagram. We conclude that the search for possible quadrupolar nematic (QN) phase is narrowed down to a field range 12.5-13 T, and remains a goal for future investigations. Results in this thesis are compared to the recent work by Grafe et al. [1]. Also, we summarize most important work on similar compound LiCuVO_4, which is investigated for 15 years and available in form of single crystals.

Abstract (croatian)

Potraga za novim(kvantnim) stanjima materije je jedan od važnijih ciljeva moderne fizike. Spinska nematska stanja, gdje spinovi formiraju stanja s iščezavajućim dipolnim momentom, dok kompleksniji operatori imaju ne iščezavajuće vrijednosti, predviđeni su u jednodimenzionalnim (1D) spinskim sustavima s feromagnetskom interakcijom među prvim i antiferomagnetskom interakcijom među drugim susjedima u području blizu saturacijskog polja. Nakon desetljeća, uglavnom teorijskih, radova u niskodimenzionalnim spinskim sustavima, prvi spojevi kandidati počeli su se pojavljivati, iako do sada nema jasnih eksperimentalnih dokaza za postojanje takvih faza. U ovom radu prezentirano je iscrpno eksperimentalno istraživanje spoja LiCuSbO_4, kandidata za opažanje spinske nematske faze. Ovaj spoj pokazuje sljedeća svojstva: nepostojanje3D uređenja u nultom magnetskom polju na temperaturama iznad 30 mK i saturacijsko polje od ≈13 T. U ovom su radu korištene tehnike nuklearne magnetske rezonancije (NMR), mionske spinske rotacije (μSR) i magnetske susceptibilnosti (SQUID) kako bi se istražili različiti dijelovi faznog dijagrama. Zaključujemo da je potraga za mogućom kvadrupolnom nematskom (QN) fazom sužena na područje izmedu 12.5 i 13 T i ostaje ciljem za buduća istraživanja. Rezultati predstavljeni u ovom radu uspoređeni su s nedavnim radom Grafea i suradnika [1]. Također, saželi smo najvažnije radove na sličnom spoju LiCuVO_4, koji je predmet istraživanja više od 15 godina i dostupan je kao monokristal.

• Keywords: frustration; 1D; spinchain; NMR; μSR.
• Keywords (croatian): Rad ne sadrži ključne riječi na drugom jeziku.
• Language: english
• URN:NBN: urn:nbn:hr:217:231132
• Promotion: 2022
• Study programme: Title: Physics; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje prirodnih znanosti, polje fizika (doktor/doktorica znanosti, područje prirodnih znanosti, polje fizika)
• Type of resource: Text
• Extent: 92 str.
• File origin: Born digital
• Access conditions: Open access
• Created on: 2022-10-11 15:33:29