Tuning Ferro- and Metamagnetic Transitions in Rare-Earth Cobalt Phosphides La_1−xPr_xCo₂P₂

Abstract

A family of rare-earth cobalt phosphides La 1-x Pr x Co 2 P 2 (0 e x e 1) that belong to the ThCr 2 Si 2 structure type has been prepared and characterized by structural and magnetic methods and electronic band structure calculations. All studied quaternary phases exhibit multiple magnetic transitions, leading to an observation of ferro-and metamagnetism and magnetic pole reversal. The ferromagnetic transition temperature of LaCo 2 P 2 (132 K) increases dramatically upon substitution of Pr for La and reaches 268 K for La 0.25 Pr 0.75 Co 2 P 2 . This increase is accompanied by elongation of intralayer Co-Co distances. Variable temperature X-ray diffraction data revealed that temperature dependences of unit cell parameters, and, correspondingly, both intra-and interlayer Co-Co separations show anomalous changes at temperatures close to the ferromagnetic transition. The electronic structure calculations reveal a strong peak in the nonmagnetic density of states (DOS). This instability is removed in the spin-polarized DOS due to the splitting of the majority and minority spin subbands, in accord with the ferromagnetic ordering in the [Co 2 P 2 ] layer.

Complex magnetic phase diagram with multistep spin-flop transitions in La0.25Pr0.75CoTan1, Garlea2, Kovnir3 et al. 2017Phys. Rev. BSelf Cite12130View full textAdd to dashboardCite

“…For instance, given the drastically different magnetic behavior of the FM LaCo 2 P 2 and AFM PrCo 2 P 2 materials, the substitution of Pr for La provides a straightforward route to modulating the exchange interactions in order to produce novel magnetic and magnetotransport properties. Indeed, our previous studies of La 1-x Pr x Co 2 P 2 showed the presence of multiple magnetic transitions in these mixed phases [14]. We found that the FM ordering temperature for the Co sublattice gradually increases with increasing Pr content (x), from 132 K for LaCo 2 P 2 to as high as 268 K for La 0.25 Pr 0.75 Co 2 P 2 .…”

“…CRYSTAL STRUCTURE As shown in our earlier report, La 0.25 Pr 0.75 Co 2 P 2 has a ThCr 2 Si 2 -type structure, space group I4/mmm [14]. The structure contains layers of R atoms and [Co 2 P 2 ] slabs alternating along the c axis (Fig.…”

“…In our earlier reports, it was shown that the magnetic properties of RCo 2 P 2 are related to the intralayer Co-Co distance, which is also correlated with the interlayer P-P separation. The substitution of La for Pr in PrCo 2 P 2 results in shorter d(Co-Co) and longer d(P-P) values [14]. In this structure type, d(Co-Co) = a/ 2, while d(P-P) is related to the unit cell parameter c and the z-coordinate of the Wyckoff position 4e (0,0,z).…”

“…La 0.25 Pr 0.75 Co 2 P 2 was prepared by annealing a mixture of elements in tin flux as reported earlier [14]. Large plate-like single crystals (1×1×0.1 mm 3 ) were selected for physical properties measurements.…”

“…Our recent studies, however, have demonstrated that substitutions into the R or Co sublattices lead to complex magnetic behavior, with coexistence of different magnetically ordered states [14][15][16][17]. For instance, given the drastically different magnetic behavior of the FM LaCo 2 P 2 and AFM PrCo 2 P 2 materials, the substitution of Pr for La provides a straightforward route to modulating the exchange interactions in order to produce novel magnetic and magnetotransport properties.…”