Mn(Pt${}_{1-x}$Pd${}_x$)${}_5$P: Isovalent Tuning of Mn Sublattice Magnetic Order

Abstract

We report the growth and characterization of MnPd${}_5$P, a ferromagnet with T${}_C$ $\approx$ 295 K, and conduct a substitutional study with its antiferromagnetic analogue MnPt${}_5$P. We grow single crystals of MnPd${}_5$P and Mn(Pt${}_{1-x}$Pd${}_x$)${}_5$P by adding Mn into (Pt${}_{1-x}$Pd${}_x$)-P based melts. All compounds in the family adopt the layered anti-CeCoIn${}_5$ structure with space group P4/mmm, and EDS and XRD results indicate that MnPt${}_5$P and MnPd${}_5$P form a solid solution. Based on magnetization and resistance data, we construct a T-x phase diagram for Mn(Pt${}_{1-x}$Pd${}_x$)${}_5$P and demonstrate the antiferromagnetic order found in MnPt${}_5$P is extraordinarily sensitive to Pd substitution. At low Pd fractions (x $<$ 0.010), the single antiferromagnetic transition in pure MnPt${}_5$P splits into a higher temperature ferromagnetic transition followed on cooling by a lower temperature ferromagnetic to antiferromagnetic transition and then by a re-entrant antiferromagnetic to ferromagnetic transition at lower temperatures. The antiferromagnetic region makes up a bubble that persists to x $\approx$ 0.009 for T $\approx$ 150 K, with all samples x $<$ 0.009 recovering their initial ferromagnetic state with further cooling to base temperature. Over the same low x range we find a non-monotonic change in the room temperature unit cell volume, further suggesting that pure MnPt${}_5$P is close to an instability. Once x $>$ 0.010, Mn(Pt${}_{1-x}$Pd${}_x$)${}_5$P undergoes a single ferromagnetic transition. The Curie temperature increases rapidly with x, rising from T${}_C$ $\approx$ 197 K at x = 0.013 to a maximum of T${}_C$ $\approx$ 312 K for x $\approx$ 0.62, and then falls back to T${}_C$ $\approx$ 295 K for pure MnPd${}_5$P (x = 1). Given that Pt and Pd are isoelectronic, this work raises questions as to the origin of the extreme sensitivity of the magnetic ground state in MnPt${}_5$P upon introducing Pd.

References in corpus (4)

• Restoring the density-gradient expansion for exchange in solids and surfaces
• Generalized gradient approximation for solids and their surfaces
• Symmetry of re-entrant tetragonal phase in Ba1-xNaxFe2As2: Magnetic versus orbital ordering mechanism
• Crystal Structure, Magnetism, and Electronic Properties of New Rare-Earth-Free Ferromagnetic MnPt5As

Cited by in corpus (1)

• Design and Predict Tetragonal van der Waals Layered Quantum Materials of MPd${}_5$I${}_2$ (M=Ga, In and 3$d$ Transition Metals)