Synthesis, crystal growth, and characterisation of selected frustrated magnets

Date

Jan 26, 2024

Time

10:00 AM - 11:00 AM

Speaker

Mirela Dragomir

Affiliation

Jozef Stefan Institute, Ljubljana, Slovenia

Language

en

Main Topic

Materialien

Host

Rita Taubert

Description

Most magnetic materials exhibit long-range magnetic order at low temperatures. In geometrically frustrated magnets, however, the topology of the lattice prevents long-range magnetic order down to temperatures close to absolute zero, often leading to exotic ground states. In my presentation, I will explore several compelling examples of such compounds. Materials with a K2NiF4-type structure have been the archetype of low-dimensional magnetism since the 1970s. With the discovery of high-temperature superconductivity in hole-doped La2CuO4 in 1986, the K2NiF4-type structure has attracted even more attention. In the first part of my talk, I will focus on the synthesis, crystal growth and magnetic properties of two groups of materials with the K2NiF4 type structure and the I4/mmm space group, namely the magnetically frustrated Ba1−xLa1+xMnO4+δ [1] and La1.6−xNd0.4SrxCuO4 superconductors [2]. The geometrically frustrated SrCu2(BO3)2 is the experimental realisation of the Shastry-Sutherland model for orthogonally interacting S = 1/2 dimers. This phase exhibits interesting magnetic plateaux and dynamic properties [3] and serves as an important test case for the understanding of quantum magnetism. A strong interplay between the crystal structure and the magnetic properties is also expected, as unique ground states such as quantum spin liquid states or superconductivity are predicted when the system is doped. However, experiments lag behind theory as the chemical doping of SrCu2(BO3)2 has not yet been sufficiently explored. The second part of my talk will focus on the synthesis and crystal growth of doped SrCu2(BO3)2 and describe the effects of different dopants on the magnetic properties. The last part of my talk will focus on NdTa7O19 which represents the first realisation of a quantum spin liquid on a triangular spin lattice with dominant Ising exchange interaction [4]. With current studies performed solely on powders, single crystals are essential for a more complete understanding of the magnetic interactions. In this talk, I will present a flux method that we developed for the growth of NdTa7O19 and related rare earth heptatantalates.

Links

• Seminars at the IFW

Last modified: Jan 26, 2024, 7:35:07 AM