Effects of substituting rare-earth ion R by non-magnetic impurities in $R_2BaNiO_5$ - theory and numerical DMRG results

TL;DR

This study investigates how replacing rare-earth ions with non-magnetic impurities in $R_2BaNiO_5$ affects its magnetic properties, revealing bound states and their experimental implications through theoretical and numerical methods.

Contribution

It introduces a combined strong-coupling and DMRG approach to analyze impurity effects in $R_2BaNiO_5$, highlighting the formation of spin-wave bound states.

Findings

Bound states form at impurity sites.

Impurities influence magnetic excitation spectra.

Experimental signatures of bound states are identified.

Abstract

In this paper we study the effect of substituting R (rare-earth ion) by non-magnetic ions in the spin-1 chain material $R_2BaNiO_5$. Using a strong-coupling expansion and numerical density matrix renormalization group calculations, we show that spin-wave bound states are formed at the impurity site. Experimental consequences of the bound states are pointed out.