Colossal magnetoresistance in EuZn${}_2$P${}_2$ and its electronic and magnetic structure

Abstract

We investigate single crystals of the trigonal antiferromagnet EuZn${}_2$P${}_2$ ($P\overline{3}m1$) by means of electrical transport, magnetization measurements, X-ray magnetic scattering, optical reflectivity, angle-resolved photoemission spectroscopy (ARPES) and ab-initio band structure calculations (DFT+U). We find that the electrical resistivity of EuZn${}_2$P${}_2$ increases strongly upon cooling and can be suppressed in magnetic fields by several orders of magnitude (CMR effect). Resonant magnetic scattering reveals a magnetic ordering vector of $q=(00\frac{1}{2})$, corresponding to an $A$-type antiferromagnetic (AFM) order, below $T_{\mathrm{N}}=23.7\mathrm{K}$. We find that the moments are canted out of the $a-a$ plane by an angle of about $40^{\circ }\pm 10^{\circ }$ degrees and aligned along the [100] in the $a-a$ plane. We observe nearly isotropic magnetization behavior for low fields and low temperatures which is consistent with the magnetic scattering results. The magnetization measurements show a deviation from the Curie-Weiss behavior below $\approx 150\mathrm{K}$, the temperature below which also the field dependence of the material's resistivity starts to increase. An analysis of the infrared reflectivity spectrum at $T=295\mathrm{K}$ allows us to resolve the main phonon bands and intra-/interband transitions, and estimate indirect and direct band gaps of $E_i^{\mathrm{opt}}=0.09\mathrm{eV}$ and $E_d^{\mathrm{opt}}=0.33\mathrm{eV}$, respectively, which are in good agreement with the theoretically predicted ones. The experimental band structure obtained by ARPES is nearly $T$-independent above and below $T_{\mathrm{N}}$. The comparison of the theoretical and experimental data shows a weak intermixing of the Eu 4$f$ states close to the $\Gamma$ point with the bands formed by the phosphorous 3$p$ orbitals leading to an induction of a small magnetic moment at the P sites.

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• Electronic band reconstruction across the insulator-metal transition in colossal magnetoresistive EuCd2P2
• Superexchange Interaction in Insulating EuZn${}_2$P${}_2$
• Carrier-induced transition from antiferromagnetic insulator to ferromagnetic metal in the layered phosphide EuZn${}_2$P${}_2$
• Manipulating magnetism and transport properties of EuCd${}_2$P${}_2$ with a low carrier concentration
• Ambient and high pressure studies of structural, electronic and magnetic properties of EuZn${}_2$P${}_2$ single crystal
• Incommensurate broken helix induced by nonstoichiometry in the axion insulator candidate EuIn${}_2$As${}_2$
• Recent advances in understanding and manipulating magnetic and electronic properties of Eu$M_2{X}_2$ ($M$ = Zn, Cd; $X$ = P, As)
• Spectroscopic signatures of magnetization-induced band renormalization and strong spin-charge-lattice coupling in EuZn${}_2$As${}_2$
• Non-relativistic linear Edelstein effect in helical EuIn2As2
• Synthesis of europium-based crystals containing As or P by a flux method: attempts to grow EuAgP single crystals
• Interplay of short-range bond order and A-type antiferromagnetic order in metallic triangular lattice GdZn${}_3$P${}_3$
• Engineering a Correlated Narrow-Gap Semiconductor: Effects of Ga Substitution in EuZn${}_2$P${}_2$