Terahertz Spectroscopy and Low Temperature Physics

Terahertz Spectroscopy and Low Temperature Physics research head is Dr. Toomas Rõõm and current projects are as follows:

1. Interaction of THz radiation with magnetic excitations, IUT 23-3

Project duration: 01.01.14 – 31.12.19

Principal Investigator: Dr. Toomas Rõõm

THz spectroscopy is one of the most powerful methods for probing magnetic excitations in solids. We will use this method to study magnetoelectric coupling in multiferroics and critical effects in different classes of magnetic materials. Magnetoelectric interaction in multiferroics mutually couples magnetization and polarization to electric and magnetic fields, thus offering new design concepts for memories and other electronic devices. Regarding more exotic effects, we will endeavour to observe critical opalescence related to critical end points, and other signatures of giant fluctuations in the vicinity of (quantum) critical points. We will use THz spectroscopy in combination with high magnetic fields (beyond 30 T) and low temperatures (down to the milli-Kelvin range). Experimental studies will be supported by theoretical modelling of spin dynamics systems and by first-principle calculation of magnetic interactions with a particular emphasis on magnetoelastic coupling.

2. Disorder in Quantum Magnets: Dynamics and Criticality, PUT 451

Project duration: 01.01.14 – 31.12.17

Principal Investigator: Dr. Dan Hüvonen

Current research project is aimed for an experimental study of quantum many-body physics using organometallic quantum magnets as model compounds. Effect of disorder on critical behavior near quantum critical points and on spin dynamics are addressed. Project focuses on two types of quantum critical behavior, namely magnetic field and pressure induced disorder-order transitions. Additionally, origin and stability of inherent multiferroicity against disorder will be addressed. Organometallic quantum magnets serve as good testing ground due to small exchange interaction parameters, softness of lattice, ease of synthesis and introduction of disorder and more simple theoretical description compared to oxide materials. Long term goal of the project is to initiate in-house synthesis of prospective magnetic model materials. Main tools will be THz, neutron, and muon spin rotation spectroscopy and bulk probes included in PPMS system for characterization.

 

 

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