Long range magnetic ordering in a spin-chain compound, Ca$_3$CuMnO$_6$, with multiple bond distances

TL;DR

This study reports on the magnetic properties of Ca$_3$CuMnO$_6$, a quasi-one-dimensional compound, revealing two long-range antiferromagnetic transitions at low temperatures despite structural distortions.

Contribution

It provides new insights into long-range magnetic ordering in a distorted spin-chain compound with multiple bond distances, highlighting its potential for studying 'order-in-disorder' phenomena.

Findings

Two long-range magnetic transitions at 5.5 K and 3.6 K

Both transitions are of long-range type, not spin-glass

Structural distortion does not prevent long-range order

Abstract

The results of ac and dc magnetization and heat capacity measurements as a function of temperature (T = 1.8 to 300 K) are reported for a quasi-one-dimensional compound, Ca$_3$CuMnO$_6$, crystallizing in a triclinically distorted K$_4$CdCl$_6$-type structure. The results reveal that this compound undergoes antiferromagnetic ordering close to 5.5 K. In addition, there is another magnetic transition below 3.6 K. Existence of two long-range magnetic transitions is uncommon among quasi-one-dimensional systems. It is interesting to note that both the magnetic transitions are of long-range type, instead of spin-glass type, in spite of the fact that the Cu-O and Mn-O bond distances are multiplied due to this crystallographic distortion. In view of this, this compound could serve as a nice example for studying "order-in-disorder" phenomena.