On Wednesday, July 31, 2024, Naveen Singh Dhami successfully defended his doctoral thesis entitled ‘Pressure Evolutions of Electronic and Crystal Structures of Europium Compounds’. The doctoral thesis was completed as part of the Croatian Science Foundation Project HrZZ UIP-2019-04-2154, ‘Pressure- and Temperature-driven Phase Transitions in Strongly Correlated Electron Systems (PaT PiSCES)’, under the mentorship of Dr. Yuki Utsumi Boucher. The research was conducted at the Institute of Physics in the ‘Group for Research of Complex and Strongly Correlated Functional Materials’ and at the Soleil Synchrotron in France.

Strongly correlated 4f-electron systems are rich in phenomena, such as Kondo effect, valence fluctuations, quantum critical behaviour, and unconventional superconductivity. Recently, a new class of heavy-fermion superconductors have been discovered among the compounds without inversion symmetry in their crystal structures. The superconductivity in non-centrosymmetric compounds often emerges under pressure. Consequently, the non-centrosymmetric EuTGe₃ series hosting divalent Eu ions (4f⁷, J = 7/2) and exhibiting antiferromagnetic ordering at low temperature is being investigated under hydrostatic pressure.

The doctoral thesis presents a systematic study of the evolution of the electronic and crystal structures of non-centrosymmetric EuTGe₃ (T = Co, Rh and Ir) series under hydrostatic pressure using complementary experimental techniques, namely x-ray spectroscopy, x-ray diffraction, and electrical resistivity measurements. The effect of different transition metal constituents on the evolution of Eu valence under pressure, as well as the contribution of interatomic and intra-atomic charge transfer, was investigated. The Pressure-Temperature phase diagram of EuIrGe₃ was extended up to 15 GPa through electrical resistivity measurements under pressure. Further details regarding this research can be found in the doctoral thesis and in published research articles.

Naveen Dhami conducted systematic research and contributed to the implementation of the electrical resistivity measurement setup under pressure using a diamond anvil cell. This work has outlined directions for future research in the field of transport under extreme conditions at the Institute of Physics.

We congratulate Naveen on his defence and wish him the best of luck in his future endeavours!