Multifunctional L1₀‐Mn_1.5Ga Films with Ultrahigh Coercivity, Giant Perpendicular Magnetocrystalline Anisotropy and Large Magnetic Energy Product

Abstract

A new kind of multifunctional L1(0) -Mn(1.5)Ga film is demonstrated for the first time. These MBE-grown epitaxial films exhibit pronounced magnetic properties at room temperature, including ultrahigh perpendicular coercivity up to 42.8 kOe, giant perpendicular magnetic anisotropy with a maximum of 21.7 Merg/cm(3) and large magnetic energy products up to 2.60 MGOe, which allow various applications in ultrahigh density recording, spintronics, and permanent magnets.

Anomalous Hall effect in epitaxialL10-Mn1.5Ga films with variable chemical ordering

“…The anomalous Hall resistivity ρ AH was extrapolated to H=0 T from ρ xy -H curves up to ±7 T after subtracting the ordinary Hall contribution R 0 H following the empirical relationship of ρ xy = R 0 H+R s M with ρ AH =R s M. Figure 2(b) demonstrates typically the ρ AH hysteresis of MnGa films measured at various temperature from 2 to 350 K. The perfectly square ρ AH hysteresis loops reveal the strong perpendicular anisotropy, consistent well with the magnetic hysteresis curves. 23 As summarized in Fig. 2(c), ρ AH increases monotonically with T for each film and shows a large value of 2.5 μΩ.cm at 350 K for the film with S = 0.37, which is still smaller than the reported 11.5 μΩ.cm at room temperature in 30 nm D0 22 -Mn 2 Ga films grown on MgO.…”

“…22 The details of sample fabrication, structural characterizations and magnetic properties could be found elsewhere. 23 The good homogeneity and sharp interface of these films are confirmed by the streaky reflection high-energy electron diffraction (RHEED) patterns ( Fig. 1(a)), the strongly oscillatory x-ray reflection (XRR) curves (Fig.…”

“…23. The anomalous Hall resistivity ρ AH was extrapolated to H=0 T from ρ xy -H curves up to ±7 T after subtracting the ordinary Hall contribution R 0 H following the empirical relationship of ρ xy = R 0 H+R s M with ρ AH =R s M. Figure 2(b) demonstrates typically the ρ AH hysteresis of MnGa films measured at various temperature from 2 to 350 K. The perfectly square ρ AH hysteresis loops reveal the strong perpendicular anisotropy, consistent well with the magnetic hysteresis curves.…”

“…22 L1 0 -Mn 1.5 Ga films are also ideal to systematically explore the effects of electron localization and chemical disorder on the AHE, as their perfectly square hysteresis allow for highly accurate determination of ρ AH , and the chemical disorder strength could be controllably altered for tailoring the related transport behaviors. 23 In this paper we study the transport behaviors in perpendicularly magnetized L1 0 -Mn 1.5 Ga films as a function of degree of long-range chemical ordering (S) and temperature (T). We observed significant quantum transport of weak localization in highly disordered films.…”

“…1(b)) and transmission electron microscopy images. 23 The films were patterned into 60×300 μm 2 Hall bars using ultraviolet photolithography and ion-beam etching for transport measurements. Hall resistivity ρ xy was measured by physical property measurement system (PPMS) together with longitudinal resistivity ρ xx .…”