Figure 1. Crystal
structure of RCo2P2. The planar square
nets of Co atoms are highlighted with gray.
Figure 2. Temperature dependence of magnetic
susceptibilities of La1-xPrxCo2P2.
The central focus of this
project is on the magnetic and structural properties of
rare-earth cobalt phosphides with the ThCr2Si2-type
structure (Fig. 1). While ternary phosphides RCo2P2
(R = La, Ce, Pr, Nd, Sm) show rather simple magnetic
behavior,1 quaternary phases La1-xPrxCo2P2
exhibit multiple magnetic transitions, leading to the
observation of such interesting phenomena as metamagnetism
and magnetic pole reversal.2,3 The ferromagnetic
transition temperature of LaCo2P2 (TC
= 132 K) is dramatically raised upon substitution of R for
La, reaching almost room temperature for La0.12Pr0.88Co2P2
(Fig. 2). This is in drastic contrast to the isostructural
(E = Si, Ge) phases,4 in which the ferromagnetic
transition remains essentially unaffected by the
substitutions in the rare-earth sublattice.
The increase in the
ferromagnetic ordering temperature can be rationalized by
the analysis of the calculated spin-polarized density of
states, which reveals a larger difference in the population
of the majority and minority spin subbands for the higher R
content.2 This leads to stronger intralayer
exchange interactions between the Co centers. The observed
magnetic and structural properties prompt investigation of
the rare-earth cobalt phosphides under high applied pressure
and/or magnetic field, which might lead to detection of new
magnetic and/or structural transitions. The exact nature of
the observed magnetic ordering will be probed with neutron
diffraction and XMCD, experiments that are currently
Reehuis, M.; Jeitschko, W.
J. Phys. Chem. Solids 1990, 51,
Kovnir, K.; Thompson, C.
M.; Zhou, H. D.; Wiebe, C. R.; Shatruk, M. Chem.
Mater. 2010, 22, 1704-1713.
Thompson, C. M.; Arico,
A.A.; Kovnir, K; Shatruk, M. J. Appl. Phys.
2010, 107, 09E316/1-3.
Acet, M.; Dincer, I.; Elmali, A.; Elerman, Y. J.
Magn. Magn. Mater. 2007, 309, 40-53.