Seminar in Physics: Resonant and non-resonant x-ray scattering studies on the rare earth iron borate multiferroics and on the iron chalcogenides

Title: Resonant and non-resonant x-ray scattering studies on the rare earth iron borate multiferroics and on the iron chalcogenides

Speaker: Dr Dinesh Kumar Shukla

Venue: L3 Lecture Hall

Time: 3 pm

Abstract:

Resonant and non-resonant x-ray scattering is an element specific, nondestructive,powerful tool for the investigations of various exotic orderings such as charge density waves, spin density waves, orbital ordering, and magnetic ordering, occurring in correlated electron materials. In this presentation I will first give an introduction to the concept of resonant and non-resonant magnetic x-ray scattering, experimental setup and essential theoretical background. Second part of presentation will be focused on x-ray scattering measurements on the rare earth iron borate multiferroics, RFe3 (BO3 )4 , where R = Ho and Sm, and on the iron chalcogenides, Fe(Te,Se)x . On multiferroics, I will report the direct measurements of Ho, Sm and Fe moments and their magnetic anisotropies through resonant and non-resonant x-ray scattering performed at low temperatures and under high magnetic fields. Through the measurements on iron chalcogenide, I will report on first time ever observed magnetic x-ray scattering signal from Fe1.13 Te and unusual structural distortion observed in this compound which we hope would invite new ideas from theoreticians as well as from experimentalists who are engaged in establishing atheory of superconductivity in Fe based superconductors.