Pressure evolutions of electronic and crystal structures of europium compounds

doctoral thesis

• Title (croatian): Evolucije elektroničkih i kristalnih struktura spojeva europija u ovisnosti o tlaku
• Author: Naveen Singh Dhami
• Mentor: Yuki Utsumi Boucher (mentor)
• Committee member: Neven Barišić (predsjednik povjerenstva)
• Committee member: Yuki Utsumi Boucher (član povjerenstva)
• Committee member: Mario Novak (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2024-07-31, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics
• Universal decimal classification (UDC): 53 - Physics

Abstract

In this thesis, I present results of evolution of electronic and crystal structures of non-centrosymmetric EuTGe3 (T = Co, Rh and Ir) under hydrostatic pressure. Since the discovery of the first heavy-fermion superconductor CeCu2Si2, more than 30 systems have been discovered that exhibit unconventional f -electron superconductivity. Most of them belong to Ce and U compounds, and their phase diagrams are often discussed by using the Doniach model. The ground state is characterized by the competition between the Kondo effect and the Ruderman Kittel-Kasuya-Yosida (RKKY) interaction, which originates from the interaction of localized f -electrons with conduction electrons. The Kondo effect screens the magnetic moments, while the RKKY interactions stabilize the magnetic ordering. Superconductivity tends to appear near the magnetic quantum critical point (QCP). Recently, pressure induced heavy-fermion superconductors have been discovered among CeTX3 (T = Co, Rh, Ir; X = Si, Ge) with the BaNiSn3-type (I4mm) structure which does not possess inversion symmetry. They have attracted much attention due to the possible coexistence of spin-singlet and -triplet Cooper channels initiated by antisymmetric spin-orbit interaction as well as strong correlations.

Abstract (croatian)

U disertaciji su predstavljeni rezultati evolucije elektronske i kristalne strukture necentrosimetričnih EuTGe3 (T = Co, Rh i Ir) sustava pod hidrostatskim tlakom. Od otkrića prvog teškofermionskog supravodiča CeCu2Si2, otkriveno je više od 30 sustava koji pokazuju nekonvencionalnu f-elektronsku supravodljivost. Većina njih pripada spojevima Ce i U, a njihovi fazni dijagrami često se diskutiraju u okviru Doniachovog modela. Osnovno stanje karakterizirano je natjecanjem Kondo efekta i Ruderman-Kittel-Kasuya-Yosida (RKKY) interakcije. Obje interakcije proizlaze iz interakcije lokaliziranih f -elektrona s metaličnim elektronima. Kondo efekt zasjenjuje magnetske momente, dok RKKY interakcija stabilizira magnetsko uređenje. Supravodljivost se obično pojavljuje blizu magnetske kvantne kritične točke (QCP). Nedavno je otkrivena tlakom inducirana supravodljivost u teškofermionskom sustavu CeTX3 (T = Co, Rh, Ir; X = Si, Ge) s BaNiSn3-tipom (I4mm) strukture koja ne posjeduje inverzijsku simetrije. Ovi sustavi su privukli veliku pažnju zbog moguće koegzistencije spinsingletnih i -tripletnih Cooperovih kanala iniciranih antisimetričnom spin-orbit interakcijom, kao i jakim korelacijama.

• Keywords: High-pressure; Strongly correlated electron system; Eu valence; Intermediate valence; Non-centrosymmetric crystal structure
• Keywords (croatian): Visoki tlak; Jako korelirani elektronski sustavi; Eu valencija; Srednja valencija; Necentrosimetrična kristalna struktura
• Language: english
• URN:NBN: urn:nbn:hr:217:189091
• Promotion: 2024
• 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
• Public note: Ovaj rad nastao je u okviru projekta HRZZ DOK-2018-09-9906.
• Created on: 2024-09-09 11:53:24