(Ca,Na)(Zn,Mn)2As2: A new spin and charge doping decoupled diluted ferromagnetic semiconductor

Abstract

Here we report the successful synthesis of a spin-& charge-decoupled diluted magnetic semiconductor (Ca,Na)(Zn,Mn) 2 As 2 , crystallizing into the hexagonal CaAl 2 Si 2 structure. The compound shows a ferromagnetic transition with a Curie temperature up to 33 K with 10% Na doping, which gives rise to carrier density of n p~1 0 20 cm -3 . The new DMS is a soft magnetic material with H C <400 Oe. The anomalous Hall effect is observed below the ferromagnetic ordering temperature.With increasing Mn doping, ferromagnetic order is accompanied by an interaction between the local spin and mobile charge, giving rise to a minimum in resistivity at low temperatures and localizing the conduction electrons. The system provides an ideal platform for studying the interaction of the local spins and conduction electrons. PACS number(s): 75.50. Pp, 75.30.Kz, 76.75.+i 2 Diluted magnetic semiconductors (DMS) have received much attention due to their potential for application in the field of spintronics [1][2][3][4][5] . In typical III-V DMS systems, such as (Ga,Mn)As, (In,Mn)As and (Ga,Mn)N, substitution of divalent Mn atoms into trivalent Ga or In sites leads to severely limited chemical solubility, resulting in metastable specimens only available as epitaxial thin films. Moreover, the hetero-valence substitution, which simultaneously dopes both charge and spin, makes it difficult to individually control each quantum degree of freedom.Recently, a new type of DMS, Li(Zn,Mn)As (termed "111" following the three chemical composition ratios), was discovered by Deng et al, The "122" DMS (Ba,K)(Zn,Mn) 2 As 2 shares the tetragonal ThCr 2 Si 2 structure with the "122" iron pnictide superconductor (Ba,K)Fe 2 As 2 and the antiferromagnet BaMn 2 As 2 9 , each with a lattice mismatch of less than 2%, giving rise to the unprecedented possibility of designing various interface-based devices among DMS, superconductors and magnets. Moreover, an increase in the carrier density could enhance the Curie temperature further to 230K in this 122 system. 10The idea of decoupling spin and charge has since been extended, resulting in the discovery of two 3 additional DMS system, "111" type Li(Zn,Mn)P 11 and "1111" types (La,Ca)(Zn,Mn)SbO & (La,Ca)(Zn,Mn)AsO 12,13 Depending on the composition, "122" compounds can crystallize into the tetragonal ThCr 2 Si 2 structure, as in the case of (Ba,K)(Zn,Mn) 2 As 2 , or the hexagonal CaAl 2 Si 2 structure. Interestingly, the hexagonal compounds CaMn 2 As 2 and CaMn 2 Sb 2 are fully frustrated classical magnetic systems with a honeycomb lattice of Mn atoms, exhibiting a complex magnetic phase diagram. 14 Here we report the synthesis of bulk specimens of a new DMS (Ca,Na)(Zn,Mn) 2 As 2 with the hexagonal CaAl 2 Si 2 structure, as shown in Fig. 1(a). ExperimentalPolycrystalline samples of (Ca,Na)(Zn,Mn) 2 As 2 were synthesized via the solid-state reaction method. The synthesis of starting materials CaAs and Na 3 As was described in an earlier paper. 8These starting materials were mixed with high-purity Zn, M...

Anomalous critical point behavior in dilute magnetic semiconductor (Ca,Na)(Zn,Yu1, Liu2, Zhao3 et al. 2020Phys. Rev. MaterialsSelf Cite4160View full textAdd to dashboardCite

“…Compared with n p ~ 3.1×10 19 cm -3 in undoped CaZn 2 Sb 2 , the 10% Na doping has thus resulted in a prominent increase of hole concentration in the material. One should note here that the value of n p observed in (Ca 0.9 Na 0.1 )(Zn 0.9 Mn 0.1 ) 2 Sb 2 is comparable to that typically seen in other DMSs in which ferromagnetism is mediated by mobile carriers, such as (Ga,Mn)As, Li(Zn,Mn)As, (Ba,K)(Zn,Mn) 2 As 2 , as well as the analogue of the material presently investigated, (Ca,Na)(Zn,Mn) 2 As 2 [15,16,29,30,31,32].…”

Single Crystal Growth and Spin Polarization Measurements of Diluted Magnetic Semiconductor (BaK)(ZnMn)2As2

“…the "111" type Li(Zn,Mn)As、 "122" type (Ba,K)(Zn,Mn) 2 As 2 and "1111" type (La,Ca)(Zn,Mn)SbO, which are named by the chemical ratio of their parent phases. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Among these new DMSs, the ThCr 2 Si 2 type (Ba,K)(Zn,Mn) 2 As 2 has a Curie temperature (Tc) up to 230 K which marks the current reliable record Tc for DMSs where ferromagnetism is mediated by carriers. [12][13] The (Ba,K)(Zn,Mn) 2 As 2 is believed to be one of milestone materials for the research of DMSs.…”

Li(Zn,Co,Mn)As: A bulk form diluted magnetic semiconductor with Co and Mn co-doping at Zn sites

“…After this discovery, several new types of bulk forms of DMSs with decoupled spins and charges injections have been reported. [17][18][19][20][21][22][23][24][25][26][27] The availability of bulk forms of specimens make it possible to investigate the microscopic magnetism of DMSs based on typical bulk probes, 28 such as nuclear magnetic resonance (NMR), 29 muon spin relaxation (µSR), 17,18,20,30 neutron scattering, absorption spectroscopy (XAS), 31 resonance photoemission spectroscopy (RPES), 31 and angle-resolved photoemission spectroscopy (ARPES). 32 It has been confirmed by the XAS measurements that the valence of Mn in (Ba,K)(Zn,Mn) 2 As 2 is bivalence.…”