The Magnetovolume Effect of an Amorphous Magnet Gd₆₇Ni₃₃

Abstract

We have observed a large magnetovolume effect in a melt spun Gd-rich amorphous magnet Gd 67 Ni 33 . The magnet shows the forced volume magnetostriction of a positive value of 3:76 Â 10 À5 T À1 at 4.4 K, which is almost as same as that of a typical Invar alloy Fe 65 Ni 35 , and the spontaneous volume magnetostriction of 1:97 Â 10 À3 at 6.9 K. Both volume magnetostrictions are proportional to the square of temperature. They are explained in the framework of spin fluctuation theory for weak itinerant electron magnets. The effect supports that the Ni constituent has a magnetic moment in the amorphous phase with such a low Ni concentration unlike crystalline Gd-Ni compounds. We propose a simple relation of estimating the magnetic moment which causes the magnetovolume effect. It gives the Ni moment of 0.61 B per atom at 0 K and the magnetovolume coupling constant of 1:20 Â 10 À14 A À2 m 2 . We also discuss the arrangement of the magnetic moment in the ground state.

Enhanced magnetopiezoelectric effect at the Néel temperature in CaMn2Bi2

“…Furthermore, the slight change of antiferromagnetic moments could produce a large dis-tortion around T N because of the magneto-volume effect [46]. In itinerant magnets in which the magnetization mainly originates from the polarization of band electrons, it is known that thermal expansion tends to diverge at the magnetic transition temperature [47][48][49][50]. This effect is called a magneto-volume effect, and has been studied in various itinerant magnets [47][48][49][50].…”

“…In itinerant magnets in which the magnetization mainly originates from the polarization of band electrons, it is known that thermal expansion tends to diverge at the magnetic transition temperature [47][48][49][50]. This effect is called a magneto-volume effect, and has been studied in various itinerant magnets [47][48][49][50]. It was theoretically proposed in the framework of the self-consistent renormalization theory [51,52] that spin fluctuations near the magnetic transition temperature enhance the magneto-volume effect, as observed in MnSi [48], Gd 67 Ni 33 [49], and β-Mn…”

“…This effect is called a magneto-volume effect, and has been studied in various itinerant magnets [47][48][49][50]. It was theoretically proposed in the framework of the self-consistent renormalization theory [51,52] that spin fluctuations near the magnetic transition temperature enhance the magneto-volume effect, as observed in MnSi [48], Gd 67 Ni 33 [49], and β-Mn…”

Effect of rapid quenching on the magnetic state, electrical resistivity and thermomagnetic properties of Gd3Co

“…Thus, the magnetic state of the amorphous Gd 3 Co alloy should be rather characterized as a ferrimagnetic one. It is worth to mention that the magnetic moment m Co ¼ 0.85 m B on Co atoms was reported to exist in amorphous Gd 65 Co 35 [23].…”