Metamagnetism

About: Metamagnetism is a research topic. Over the lifetime, 2023 publications have been published within this topic receiving 38108 citations.

Tuning the magnetic entropy change of Ni50-xMn35+xIn15 alloys by varying the Mn content

Abstract: Magnetocaloric effect associated with the first-order martensitic transition (TM) is investigated in polycrystalline Ni50−xMn35+xIn15 alloys with varying Mn content but fixing In content. It is found that when Mn content reaches x=3, a field-induced metamagnetic transition takes place. An external magnetic field can reduce TM to a lower temperature at a rate of 3.5 K/T, thereby yielding a large magnetic entropy change ΔS near room temperature. The ΔS magnitude attains to 33 J/kg K under a magnetic field of 5 T at 285 K for the sample with x=3, while the temperature span of the ΔS peak can reach 15 K because of the reduction in TM by the external magnetic field. The calculated refrigerant capacity reaches 279 J/kg for the sample with x=3. These values of the magnetocaloric parameters suggest that these alloys are suitable candidates for magnetic refrigerants.

Magnetic transition and coercivity in TbMn6Sn6

Abstract: In the present paper, the structure and magnetic properties of TbMn6Sn6 have been investigated. TbMn6Sn6 is found to be of HfFe6Ge6-type structure (space group P6/mmm) with a = 5.5461 Angstrom, c = 9.0477 A and V = 241 Angstrom(3). This compound shows ferrimagnetic behaviour with the ordering temperature T-c = 421 K. A peak is also observed in the thermal magnetic curve at 330 K. Under magnetic fields of 100, 300 and 400 Oe, the magnetization values first increase with increasing temperature, next exhibit a peak and then decrease with further increase in temperature. When the applied magnetic field is sufficiently large, e.g. 1000 and 2100 Oe, the magnetization of the whole sample decreases with increasing temperature. With increasing temperature from the range 77-300 K, the coercivity first increases, next undergoes a peak at about 200 K and then decreases. At room temperature a magnetization jump is observed in the magnetization curves at a field of about 4 kOe in both the aligned and the free powder samples. This jump may be attributed to the spin-flop or metamagnetic transition. The magnetic anisotropy field at room temperature is found to be 8.33 kOe.

Influence of Fe and Co additions on magnetization and magnetoresistivity of MnAu2 melt-spun alloys

Abstract: Melt-spun MnAu2 ribbons modified by ternary magnetic additions (Fe and Co) show a large giant magnetoresistance (GMR) effect up to a magnetoresistance ratio MR={[R(H=7T)−R(0)/R(0)]} of the order of −10% at room temperature. Pure MnAu2 samples show a transition from positive magnetoresistance at low temperatures (e.g., MR=+23% at 10 K and μ0H=5 T) to a GMR behavior with values of about −8% at 295 K and 5 T. At 135 K the resistivity is nearly independent of the applied magnetic field. The strong increase of |MR| at room temperature is only found with applied fields larger than a threshold field, where a metamagnetic transition occurs. Alloying the compound with Co or Fe this threshold field can be reduced or suppressed. This effect is due to softening of the antiferromagnetic behavior of the (Mn; Co or Fe)Au2 samples. For an alloy with 5 at. % Fe as substitutes for Mn, no metamagnetic transition is observed in the temperature range between 10 and 300 K. For both 5 at. % Co or Fe additions a GMR behavior is ...

Itinerant electron magnetism of hexagonal La2Ni7

Abstract: Magnetizations of itinerant electron magnets La 2 Ni 7 and related compounds with a hexagonal crystal structure were measured. Successive metamagnetic transitions were observed in La 2 Ni 7 , and H-T phase diagram of La 2 Ni 7 was determined. The zero-field state may be antiferromagnetic for T < T t1 = 54 K, and is a state of some kind (probably antiferromagnetic) with a very small ferromagnetic moment in T t1 < T < T t2 = 66K. Substitutions of Co or Cu for Ni show that the band structure of La 2 Ni 7 tends to produce both ferromagnetic and antiferromagnetic states, favoring the application of the theory of Moriya and Usami. Their theory is applicable assuming a tendency to form two types of antiferromagnetic states and a tendency to form a ferromagnetic state.