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Trinanjan Datta

Publications and source records attributed to Trinanjan Datta.

40 records · Page 3Linked to original sources
arXiv2008

The magnetoelectric coupling in the multiferroic compound LiCu2O2

We investigate the possible types of coupling between ferroelectricity and magnetism for the zig-zag spin chain multiferroic LiCu2O2 compound. We construct a multi-order parameter phenomenological model for the material based on a group theoretical analysis. From our calculation we conclude that a coupling involving the inter-chain magnetic structure and ferroelectricity is necessary to understand the experimental results of Park et.al. Our proposed model is able to account for the electric polarization flop in the presence of an externally applied magnetic field. Furthermore, based on our theoretical model we can make specific selection rule predictions about electromagnon excitations present in the LiCu2O2 system. We also predict that the electromagnon peaks measured in an ac-conductivity measurement are field dependent.

cond-mat.str-el↗
arXiv2007

Theoretical study of interacting electrons in one dimension - ground states and experimental signatures

This dissertation focuses on a theoretical study of interacting electrons in one dimension. The research elucidates the ground state (zero temperature) electronic phase diagram of an aluminum arsenide quantum wire which is an example of an interacting one dimensional electron liquid. Using one dimensional field theoretic methods involving abelian bosonization and the renormalization group we show the existence of a spin gapped quantum wire with electronic ground states such as charge density wave and singlet superconductivity. The superconducting state arises due to the unique umklapp interaction present in the aluminum arsenide quantum wire bandstructure discussed in this dissertation. It is characterized by Cooper pairs carrying a finite pairing momentum. This is a realization of the Fulde-Ferrell-Larkin- Ovchinnikov state which is known to lead to inhomogeneous superconductivity. The dissertation also presents a theoretical analysis of the finite temperature single hole spectral function of the one dimensional electron liquid with gapless spin and charge modes (Luttinger liquid). The hole spectral function is measured in angle resolved photoemission spectroscopy experiments. The results predict a kink in the effective electronic dispersion of the Luttinger liquid. A systematic study of the temperature and interaction dependence of the kink provides an alternative way to detect spincharge separation in one dimensional systems where the peak due to the spin part of the spectral function is suppressed.

cond-mat.str-el↗
arXiv2007

The Luttinger liquid kink

Although the Tomonaga-Luttinger liquid exhibits spin-charge separation and the electron is not an elementary excitation of the system, nevertheless an effective electronic dispersion may be defined by the frequency-dependent peak in the momentum distribution curve (MDC). The MDC is defined by considering the single hole spectral function $A^<(\vec{k},ω)$ as a function of $\vec{k}$ at a fixed frequency $ω$. We show the existence of a \emph{kink} in this dispersion for the spin-rotationally invariant Tomonaga-Luttinger liquid at finite temperature. In the repulsive regime where the charge velocity $v_{c}$ is greater than the spin velocity $v_{s}$, the low frequency effective electronic dispersion is linear in $\vec{k}$ and follows a velocity $v_l$ between the spin and charge velocities, $v_s < v_l < v_c$. The high frequency part (which is also linear in $\vec{k}$) disperses with the charge velocity $v_c$. The energy scale of the crossover between the two velocities defines a kink, $E_{\rm kink}$. In addition, the high energy dispersion extrapolates to the Fermi energy at a wavevector $k_{ex} \ne k_F$ which is shifted from the Fermi wavevector. The presence of such a kink is measurable with, {\em e.g.}, angle-resolved photoemission experiments, and may be used to test for the presence of Luttinger liquid behavior in systems in which the separate contributions from spin and charge to the MDC are not discernible due to strong interactions or low experimental resolution.

cond-mat.str-el↗