Andreev reflection spectroscopy of ferromagnetic Fe_0.26TaS₂ with layered structure

Abstract

<sec>An elementary mission of spintronics research is to prevent the interface reacting in spin device and extract spin polarization of ferromagnetic material reliably. Layered transition metal sulfide has very strong anisotropic magnetism, magnetoresistance, and unique Hall effect. It provides a good platform for studying the magnetic order related physical phenomena and may lay a foundation for spintronic applications. In this work, the magnetism, electronic transport and Andreev reflection spectrum of a novel ferromagnetic material Fe<sub>0.26</sub>TaS<sub>2</sub> with a layers-stacked structure are measured. Strong magnetic anisotropy, double-peak magnetoresistance and anomalous Hall effect are found. In the magnetic measurement, the strong magnetic anisotropy behavior in Fe<sub>0.26</sub>TaS<sub>2</sub> single crystal is observed. Curie temperature <i>T</i><sub>C</sub> of the Fe<sub>0.26</sub>TaS<sub>2</sub> single crystal is confirmed by zero field cooling, field cooling and Arrot plot. The electronic transport in the Fe<sub>0.26</sub>TaS<sub>2</sub> single crystal also reveals strong anisotropic behaviors, such as butterfly-like magnetoresistance and obvious anomalous hall effect below <i>T</i><sub>C</sub>.</sec><sec>To obtain the spin polarization of Fe<sub><i>x</i></sub>TaS<sub>2</sub>, we fabricate an Fe<sub><i>x</i></sub>TaS<sub>2</sub>/superconductor Andreev junction to measure the spin polarization that is fitted by the modified Blonder-Tinkham-Klapwijk (BTK) theory. Perhaps the diffusion of Pb can form an alloy structure, creating another superconductor behavior. The two-gap BTK theory confirms our hypothesis, and the result spin polarization can reach 26%. To avoid the interference from Pb alloy superconductor, we also fabricate an Fe<sub>0.26</sub>TaS<sub>2</sub>/Al/Pb superconductor junction by evaporating Al and then Pb film on the surface of Fe<sub>0.26</sub>TaS<sub>2</sub> in sequence. The results of BTK fit show that the spin polarization from the first technical route cannot be reliable due to the tunneling layer on the Al interface. In order to obtain a clean interface, Fe<sub>0.26</sub>TaS<sub>2</sub>/NbSe<sub>2</sub> junction is fabricated through mechanical-exfoliation and dry-transfer method. Through the Andreev reflection spectrum of this junction, the spin polarization of Fe<sub>0.26</sub>TaS<sub>2</sub> is extracted to be 47% ± 7%. For various two-dimensional ferromagnetic materials, our work suggests that the dry-transfer method is well applicable in spin polarization extraction. The results of spin polarization indicate that the Fe<sub>0.26</sub>TaS<sub>2</sub> is a promising candidate of next-generation material of spintronics.</sec>

Anisotropic Magnetoresistance Effect of Intercalated Ferromagnet FeTa3S6

“…Recently, Dzyaloshinskii-Moriya interaction (DMI) confirmed in topological structures such as magnetic skyrmions was also confirmed in Fe 0.28 TaS 2 nanoplates; this shows a large topological Hall effect, which confirms the DMI in a transition metal dichalcogenide by dual intercalation [29][30][31][32]. In addition, the ferromagnet Fe x TaS 2 also exhibits many peculiar magnetic properties, such as sharp switching of magnetization [26], strong magnetocrystalline anisotropy [33], butterfly-shaped double-peak magnetoresistance [27], anomalous Hall effect [34], and anisotropic magnetoresistance effect [33].…”

“…For example, Cu or Pd intercalation induces superconductivity in 1T-TiSe 2 [18,19], and 3d transition metal intercalation leads to different kinds of long-range magnetic order in TMDs (such as TiS 2 ) [20]; among the compounds with Cr-intercalated NbS 2 , Cr 1/3 NbS 2 is a chiral helimagnet, which confirms the strong coupling between neighboring layers [21,22]. Fe x TaS 2 is a transition metal dichalcogenide of magnetic element intercalation 2H-TaS 2 , which exhibits abundant magnetic properties [23][24][25][26][27][28][29][30][31][32][33][34]. It is in the spin glass state for x < 0.2, ferromagnetic for 0.2 ≤ x ≤ 0.4, and antiferromagnetic for x > 0.4 [23,24].…”

Structure, magnetism and magnetocaloric effects in Er5Si3B x (x = 0.3,0.6) compounds

“…Magnetic materials have gained great interest due to their attractive properties and wide applications. [1][2][3][4][5][6][7] The novel solid-state refrigeration technology based on the magnetocaloric effect (MCE) is one of the most promising replacements for conventional refrigeration technologies because of its high efficiency and non-emission of pollutants. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] The MCE is the thermodynamic response of the magnetic material to an applied magnetic field, meaning that the magnetic moment transforms from ordered to disordered (or ordered to ordered) during the imposition of an applied magnetic field, resulting in a change in magnetic entropy.…”

Magnetic and magnetotransport properties of layered TaCoTe2 single crystals

“…Since the discovery of graphene, two-dimensional (2D) materials have proved to be a fertile ground to explore novel electrical, [1][2][3][4] optical, [5][6][7] mechanical, [8,9] and magnetic properties. [10][11][12][13] In 2D materials, it has been confirmed that the decrease in the crystal dimension makes it sensitive to carrier concentration, magnetic field, pressure and electric field, and novel phenomena that are different from the bulk crystal can be observed, such as the observation of the quantum Hall effect in graphene, [14] the strongly thickness-dependent metallic to semiconductor, charge density wave, or superconducting phases in transition metal dichalcogenides, [15,16] the layer-dependent ferromagnetism in 2D magnetic materials, [17,18] the observation of the quantum anomalous Hall effect in few-layer MnBi 2 Te 4 , [19] and the enhancement of a weak-antilocalization signature in Nb 3 SiTe 6 . [20] During the past decade, a number of important potential applications have been proven in 2D materials.…”