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Pradeep KumarDepartment of
Physics (352) 672-1931 phone |
I am affiliated with the National High Magnetic Field Laboratory as well as with the Institute for Fundamental Theory
My research interests are in the field of condensed matter theory. The current activities are in the area of (the numbers refer to the papers in the list of publications):
Metamagnetism (112, 113, 114,
116, 117): Metamagnetism refers to a discontinous change in the
magnetization at a critical field Bc. It happens at low
temperatures and is associated with a peak in the temperature dependence
of the low field linear susceptibility. Shivaram et al discovered that
nonlinear susceptibilities also contained peaks in their temperature
dependence which scales with the critical field. One could say that in
spite of the complex electronic structure of the materials involved,
there is really only one energy scale that dominates metamagnetic
behavior. A model built with a single energy scale shows many of the
observed features. There are thermodynamic identities that help
understand several different experimental results.
Multiferroics (107, 110, 111,
115): Maxwell was the first to note that in vacuum, a coupling between
electric and magnetic fields is possible only at a finite frequency and
wave vector. Thus came the electromagnetic waves. In a material there
are exceptions and interesting consequences. One finds a
magnetoelectric effect (a magnetization caused by a magnetic field or an
electric dipole moment arising from a magnetic field) under special
conditions.
Higher Order Phase Transition: Was Ehrenfest right ? (79, 85, 90, 92, 97, 102, 104): Until the early 1930's, all thermodynamic phase transitions were supposed to involve a latent heat and a change in density (or some equivalent observable). What we now call a first order phase transition. Paul Ehrenfest came across two transitions, superconductivity in metals and superfluidity in Helium where there was no latent heat and no change in density, instead there was a change in specific heat and compressibility. He built a thermodynamic framework to describe those transitions as second order phase transitions and thereby opening door to yet higher order phenomena. Landau's description based on broken symmetry and the expansion of the free energy provided an alternative framwork. That has been misunderstood to conclude that there is something wrong with the Ehrenfest picture. Ehrenfest was entirely correct.
Are there phase transitions of order infinity?
