Tailoring-compensated ferrimagnetic state and anomalous Hall effect in quaternary Mn–Ru–V–Ga Heusler compounds

Cubic Mn_(2)Ru_(x)Ga Heusler compound is a typical example of compensated ferrimagnet with attractive potential for high-density,ultrafast,and low-power spintronic applications.In the form of epitaxial thin films,Mn_(2)Ru_(x)Ga exhibits high spin polarization and high tunability of compensation temperature by freely changing the Ru content x in a broad range(0.3<x<1.0).Herein Mn-Ru-Ga-based polycrystalline bulk buttons prepared by arc melting are systematically studied and it is found that in equilibrium bulk form,the cubic structure is unstable when x<0.75.To overcome this limitation,Mn-Ru-Ga is alloyed with a fourth element V.By adjusting the content of V in the By adjusting the content of V in the Mn_(2)Ru_(0.75)V_(y)Ga and Mn_(2.25-y)Ru_(0.75)V_(y)Ga quaternary systems the magnetic compensation temperature is tuned.Compensation is achieved near 300 K which is confirmed by both the magnetic measurement and anomalous Hall effect measurement.The analyses of the anomalous Hall effect scaling in quaternary Mn-Ru-V-Ga alloy reveal the dominant role of skew scattering,notably that contributed caused by the thermally excited phonons,in contrast to the dominant intrinsic mechanism found in many other 3d ferromagnets and Heusler compounds.It is further shown that the Ga antisites and V content can simultaneously control the residual resistivity ratio(RRR)as well as the relative contribution of phonon and defect to the anomalous Hall effect a"/a0'in Mn-Ru-V-Ga,resulting in a scaling relation a"/a0'∝RRR^(1.8).

Study and design of cryogenic accelerating structure and RF optimization of single cell for SXFEL energy upgrading

Purpose Recent researches of RF gun operated at cryogenic temperature have many advantages to serve as the technology to realize the future light source.In order to further improve the accelerating gradient of accelerators,the cryogenic acceleration structure is studied.Design/methodology/approach The cryogenic accelerating structure is studied by numerical analysis and simulation.Findings In this paper,the low-temperature characteristics of the material are analyzedfirstly,and then the preliminary design scheme of the cavity is proposed according to the analysis results.Furthermore,the prototype with RF coupler is designed and optimized systemically,and the modified Poynting vector distribution is calculated.Finally,the high-power test based on existed setup is also proposed.Originality/value The study of the cryogenic structure in this paper is helpful for improving the accelerating gradient and developing compact accelerators.