IIT Jodhpur
Webinar Series "Deep Diving into Physics" by Prof. C. S. Yadav titled "Magnetic monopole, spin-ice and field induced spin-freezing state in geometrically frustrated system" on 20 October 2021

The fourth speaker of the webinar series Deep Diving into Physics, Prof. C. S. Yadav, School of Basic Sciences, Indian Institute of Technology Mandi, introduced the new physics emerging from frustrtaed magentic systems to our students.

 

Abstract:

The geometrically frustrated magnetic systems exhibit a variety of interesting quantum phases, non-trivial magnetic ordering and excitations originating from the competing ferromagnetic and antiferromagnetic interactions. In pyrochlores systems of the type A2B2O7 (A = rare earth metal, B = transition metal), the exotic magnetic ground state is achieved by three competing interactions: antiferromagnetic exchange interaction, ferromagnetic dipolar interactions and crystal electric field. In some of the pyrochlores, the dominant effect of crystal electric field forces the spin to point either directly towards or away from the center of the tetrahedra and induces spin anisotropy in the system. For example, in Ho2Ti2O7 and Dy2Ti2O7, spin ice ground state is achieved by two-in and two-out configuration of spins sitting on the vertices of the tetrahedra and shows magnetic monopoles like excitations.

 

In this talk, I shall elaborate on the concept of the spin ice, and magnetic monopole followed by our studies on the effect of magnetic field and dilution of magnetism on the spin freezing state of the Dy2Zr2O7 system. We show that the low-temperature magnetic ground state of Dy2-xLaxZr2O7 system evolves from a field-induced spin ice state for La compositions of 0 £ £ 0.3 to the Dy2Ti2O7 like spin freezing near T ~ 16 K for La compositions of 1.5 £ £ 1.9.