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| Author(s): |
Leonardo Oparacz Kutelak
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Física Gleb Wataghin |
| Defense date: | 2020-10-02 |
| Examining board members: |
Ricardo Donizeth dos Reis;
Eduardo Matzenbacher Bittar;
Abner de Siervo
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| Advisor: | Ricardo Donizeth dos Reis; Flávio César Guimarães Gandra |
| Abstract | |
Rare earth hexaboride family present a rich variety of transport phenomena, ranging from superconductors up to Kondo insulators. Recently compounds such as SmB6 and YbB6 were revisited from proposals of non-trivial topology correlated to mixed-valence state in its phase diagram. This opens perspectives for exotic states on remaining family¿s compounds, mainly when using adjustment parameters like hydrostatic pressure, exploring possible connections between these well localized 4f shell electron containing ions. In this work we explore EuB6, the only compound of the family that presents well defined ferromagnetic ordering up to pressures of 17 GPa. Furthermore it also presents two transitions involving magnetic polarons formation and charge de-localization, with open discussion about it semimetallic or semiconductor behavior. At this work we observe, using X-Ray absorption spectroscopy (XAS) and synchrotron Mossbauer spectroscopy, that by applying pressures above 20 ¨ GPa using diamond anvil cells (DACs) the ferromagnetic ordering below 12 K is suppressed and substituted by a new paramagnetic phase where Eu2+ and Eu3+ coexist. viii This opens prospects for theoretical and experimental studies about physics behind the new phase observed in ambient of extreme conditions. With this, correlations between rare earth hexaborides structure, magnetic and electronic properties may be better understood with the opening of new possibilities to find and elucidate proposed non-trivial topology states for this family (AU) | |
| FAPESP's process: | 18/19015-1 - Pressure-induced exotic states in rare earth hexaborides |
| Grantee: | Leonardo Oparacz Kutelak |
| Support Opportunities: | Scholarships in Brazil - Master |