Li(Zn,Mn)As as a new generation ferromagnet based on a I–II–V semiconductor

Abstract

In a prototypical ferromagnet (Ga,mn)As based on a III-V semiconductor, substitution of divalent mn atoms into trivalent Ga sites leads to severely limited chemical solubility and metastable specimens available only as thin films. The doping of hole carriers via (Ga,mn) substitution also prohibits electron doping. To overcome these difficulties, masek et al. theoretically proposed systems based on a I-II-V semiconductor LiZnAs, where isovalent (Zn,mn) substitution is decoupled from carrier doping with excess/deficient Li concentrations. Here we show successful synthesis of Li 1 + y (Zn 1 − x mn x )As in bulk materials. Ferromagnetism with a critical temperature of up to 50 K is observed in nominally Li-excess (y = 0.05-0.2) compounds with mn concentrations of x = 0.02-0.15, which have p-type metallic carriers. This is presumably due to excess Li in substitutional Zn sites. semiconducting LiZnAs, ferromagnetic Li(Zn,mn)As, antiferromagnetic LimnAs, and superconducting LiFeAs systems share square lattice As layers, which may enable development of novel junction devices in the future.

New diluted ferromagnetic semiconductor with Curie temperature up to 180 K and isostructural to the ‘122’ iron-based superconductors

“…2c below T Hist . A very similar departure of ZFC and FC magnetization, associated with a coercive fieldB1 T, was observed in a well-known itinerant ferromagnet SrRuO 3 (refs 16,17), which has a comparable T C B160 K. The large coercive field at low temperatures in (Ba,K)(Zn,Mn) 2 As 2 is different from Li(Zn,Mn)As, which exhibits a small coercive field ofB100 G in the entire temperature region 7 . The large temperature dependence of the coercive field in (Ba,K)(Zn,Mn) 2 As 2 opens a possibility of temperature tuning of anisotropy and stability of magnetic memory.…”

“…Polycrystalline specimens of (Ba,K)(Zn,Mn) 2 As 2 were synthesized using the arcmelting solid-state reaction method similar to that described in ref. 7. Details of the synthesis and instruments used for characterization are described in the Methods section.…”

“…Polycrystalline specimens of (Ba,K)(Zn,Mn) 2 As 2 were synthesized using the arc-melting solid-state reaction method similar to that described in ref. 7. The starting materials, namely, precursors of BaAs, KAs, ZnAs, and highpurity Mn powders, were mixed according to the nominal composition of (Ba,K)(Zn,Mn) 2 As 2 .…”

“…Following a theoretical proposal by Masek et al 6 , a new system Li(Zn,Mn)As was recently synthesized by Deng et al 7 based on the I-II-V semiconductor LiZnAs, showing a Curie temperature up to T C ¼ 50 K. In this system, charges are doped via offstoichiometry of Li concentrations, while spins by the isovalent (Zn 2 þ ,Mn 2 þ ) substitutions. Although Li(Zn,Mn)As was a ferromagnetic DMS of a new type having a few distinct advantages over (Ga,Mn)As, the upper limit of currently achievable T C has been significantly lower than that in (Ga,Mn)As 2,7 .…”

Large resistivity change and phase transition in the antiferromagnetic semiconductors LiMnAs and LaOMnAs

“…In comparison to LiMnAs, where the Mn moments are ordered antiferromagnetically both in the ab Mn planes and between the Mn planes stacked along the c axis, 15 in the case of LaOMnAs, the moments are aligned antiferromagnetically in the ab plane but ferromagnetically along c. 9 Interestingly, in contrast to the expected 5 μ B of the S = 5/2 Mn 2+ ion, neutron scattering data on LiMnAs and LaOMnAs suggest a magnetic moment of approximately 3.4 to 3.8 μ B , which is close to the magnetic moment of 4 μ B for an S = 2 Mn 3+ ion. This closely resembles the simple rules and general observation made regarding Heusler compounds, 16 stating that Mn tends to have a large localized magnetic moment with an oxidation state of 3 (in the literature referred to as the Kübler's rule 17 ) in a nominal d 4 configuration. The magnetism then stems from the nonbonding d electrons, as can be best observed in half-Heusler compounds, where only Mn or rareearth-containing compounds form stable magnetic phases.…”