Magnetic Study on Y2M3Co9P7 (M: Transition Metals) with Cation-Ordered Zr2Fe12P7-Type Structure

2019 ◽  
Vol 289 ◽  
pp. 164-169
Author(s):  
Yusuke Kato ◽  
Hiroto Ohta ◽  
Hiroko Aruga Katori
Keyword(s):  
Transition Metals ◽  
Curie Temperature ◽  
Spontaneous Magnetization ◽  
Magnetic Moments ◽  
Hexagonal Structure ◽  
Type Structure ◽  
Magnetic Study ◽  
Pauli Paramagnetism ◽  
Fe And Mn ◽  
The Stability

We successfully synthesized polycrystalline samples of Y2M3Co9P7 (M = Cr, Mn, Fe, Co, Mo, and Ru), which has the Zr2Fe12P7-type hexagonal structure with M and Co selectively occupy the pyramidal site and three tetrahedral ones, respectively. For the case of M = Co, or Y2Co12P7, the itinerant electronic ferromagnetism was observed below the Curie temperature TC = 153 K. For M = Cr, Mn, Fe, and Ru, the ferromagnetism was also observed below TC = 167 K, 229 K, 233 K and 18 K, respectively, whereas for M = Mo, an exchange-enhanced Pauli paramagnetism tool the place of the ferromagnetism. Among compounds with M being 3d transition metals, TC and spontaneous magnetization took the maximum around M = Fe and Mn. This tendency was also seen in the cases of M being 4d transition metals, i.e., M = Ru and Mo. Our result indicates that magnetic moments at the pyramidal site have rather localized nature and largely affect the stability of the ferromagnetism of Y2M3Co9P7 although the ferromagnetism is considered to be mainly derived from three Co sites.

scholarly journals Forced Magnetostrictions and Magnetizations of Ni2+xMnGa1−x at Its Curie Temperature

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2115 ◽  
Author(s):  
Takuo Sakon ◽  
Yuhi Hayashi ◽  
Dexin Li ◽  
Fuminori Honda ◽  
Gendo Oomi ◽  
...  
Keyword(s):  
Curie Temperature ◽  
Spontaneous Magnetization ◽  
Spin Fluctuation ◽  
Magnetic Moments ◽  
Critical Index ◽  
Fluctuation Theory ◽  
Experimental Investigations ◽  
Valence Electron Concentration ◽  
Martensitic Transition ◽  
The Relationship

Experimental investigations into the field dependence of magnetization and the relationship between magnetization and magnetostriction in Ni2+xMnGa1−x (x = 0.00, 0.02, 0.04) alloy ferromagnets were performed following the self-consistent renormalization (SCR) spin fluctuation theory of itinerant ferromagnetism. In this study, we investigated the magnetization of and magnetostriction on Ni2+xMnGa1−x (x = 0.02, 0.04) to check whether these relations held when the ratio of Ni to Ga and, the valence electron concentration per atom, e/a were varied. When the ratio of Ni to Ga was varied, e/a increased with increasing x. The magnetization results for x = 0.02 (e/a = 7.535) and 0.04 (e/a = 7.570) suggest that the critical index δ of H ∝ Mδ is around 5.0 at the Curie temperature TC, which is the critical temperature of the ferromagnetic–paramagnetic transition. This result confirms Takahashi’s spin fluctuation theory and the experimental results of Ni2MnGa. The spontaneous magnetization pS slightly decreased with increasing x. For x = 0.00, the spin fluctuation parameter in k-space (momentum space; TA) and that in energy space (T0) were obtained. The relationship between peff/pS and TC/T0 can also be explained by Takahashi’s theory, where peff indicates the effective magnetic moments. We created a generalized Rhodes-Wohlfarth plot of peff/pS versus TC/T0 for other ferromagnets. The plot indicates that the relationship between peff/pS and T0/TC follows Takahashi’s theory. We also measured the magnetostriction for Ni2+xMnGa1−x (x = 0.02, 0.04). As a result, at TC, the plot of the magnetostriction (ΔL/L) versus M4 shows proportionality and crosses the origin. These magnetization and magnetostriction results were analyzed in terms of Takahashi’s SCR spin fluctuation theory. We investigated the magnetostriction at the premartensite phase, which is the precursor state to the martensitic transition. In Ni2MnGa system alloys, the maximum value of magnetostriction is almost proportional to the e/a.

The spontaneous magnetization of nickel + copper alloys

1958 ◽  
Vol 248 (1253) ◽  
pp. 145-152 ◽  
Keyword(s):  
Curie Temperature ◽  
Marked Decrease ◽  
Spontaneous Magnetization ◽  
Magnetic Moments ◽  
Copper Alloys ◽  
Nickel Copper ◽  
Wide Range ◽  
Magnetic Techniques ◽  
Good Agreement

The spontaneous magnetization (σ 0 , T ) of a ferromagnetic may be deduced exclusively from the determination of magnetic isothermals, or in conjunction with magnetocaloric measurements. Values of σ 0, T of a nickel + copper alloy containing 30·75 at. % of copper have been obtained near its Curie temperature using both of these techniques and are shown to be in good agreement. Measurements of spontaneous magnetization and Curie temperature ( θ f ) of nickel + copper alloys containing up to 54·11 at. % of copper using the purely magnetic techniques are described. These measurements were performed over a temperature range from θ f down to 80 °K in all cases, and to 23 °K in the cases of alloys containing over 30 at. % of copper. The magnetic moments per atom ( p B ) of the alloys, which are deduced from the measurements, vary linearly over a wide range of composition, extrapolating to p B = 0 at 53 at. % of copper. This value is in good agreement with that obtained by Meyer & Wolff (1958), and contrary to that based on the familiar measurements of Alder (1916). The reduced magnetization-temperature curves of some of the alloys are given and these show a continuous marked decrease in fullness with increasing copper content.

The spontaneous magnetization of cobalt

1951 ◽  
Vol 207 (1091) ◽  
pp. 427-446 ◽  
Keyword(s):  
Heat Treatment ◽  
Curie Temperature ◽  
Single Crystal ◽  
Transformation Temperature ◽  
Equations Of State ◽  
Spontaneous Magnetization ◽  
Hexagonal Structure ◽  
Slow Cooling ◽  
Temperature Range ◽  
The Face

The paper describes how measurements of the spontaneous magnetization of pure specimens of single-crystal close-packed hexagonal and polycrystalline face-centred cubic cobalt have been made over the temperature range -183 to 1121° C. A single crystal of cobalt possessing a close-packed hexagonal structure was prepared by the process of slow cooling of the melt. Owing to the presence of a phase change in cobalt occurring c . 400° C when the metal changes from a close-packed hexagonal structure below 400° C to a face-centred cubic structure above 400° C, it was necessary to determine two critical rates of cooling to prepare a crystal. Magnetic test specimens of single-crystal cobalt, cut so that they were capable of being magnetized along the easy axis of magnetization (the hexagonal axis), and of polycrystalline cobalt, of approximate dimensions 4 x 2 x 2 mm., were studied using the magnetic balance devised by Sucksmith (1939). The spontaneous magnetization of the hexagonal form was accurately measured from — 183 to 431° C, this latter temperature being determined as the upper transformation temperature of the cobalt. Complete tables of these measurements are given. By extrapolation the value 162.5 5 was determined for the spontaneous magnetization of hexagonal cobalt at absolute zero of temperature. Measurements on the polycrystalline face-centred cubic material were made from 394° C (this temperature being determined as the lower transformation temperature) to the Curie temperature, determined by extrapolation to be 1121° C. The face-centred cubic material possessed greater magnetization than the hexagonal, and in the temperature range 431 to 950° C it was found to be dependent upon the heat treatment the specimen had received; the significant factor in this heat treatment being the speed with which the specimen was allowed to cool through the lower transformation temperature. The Curie temperature was not affected by this heat treatment. To determine the spontaneous magnetization at very high temperatures where no saturation was observed the extrapolation technique devised by Weiss & Forrer (1926) was used. This procedure is described. When reduced values of magnetization and temperature were calculated it was found that the hexagonal and face-centred cubic materials obeyed different reduced equations of state although excellent agreement was obtained when the reduced values for face-centred cubic cobalt were compared with similar values for nickel. These results given in detailed tabulated form show that the reduced magnetic equation of state is structure dependent.

Structural and Magnetocaloric Properties of Ball Milled LaFe13−xSix(H,C)y

MRS Advances ◽  
2017 ◽  
Vol 2 (56) ◽  
pp. 3447-3452
Author(s):  
L. Bessais ◽  
M. Phejar ◽  
V. Paul-Boncour
Keyword(s):  
Curie Temperature ◽  
Magnetic Moments ◽  
Synthesis Method ◽  
Annealing Treatment ◽  
Interstitial Site ◽  
High Energy ◽  
Magnetocaloric Properties ◽  
Magnetovolume Effect ◽  
Short Annealing ◽  
Giant Magnetocaloric Effect

ABSTRACTLaFe13−xSix compounds display a giant magnetocaloric effect near 200 K. The insertion of light elements (H, C) is used to improve the Curie temperature near ambient temperature for magnetic refrigeration applications. We have developed a synthesis method with a short annealing treatment compared to classical melting techniques. The parent intermetallic alloys were synthesized by high energy ball milling. The insertion of H atoms was carried out using a Sievert apparatus and the carbon atom was inserted by solid/solid reaction. Moreover, structural and magnetic results were carried out by neutron diffraction and Mössbauer spectrometry for H content (y = 0.7,1.5) and C content (y = 0.7). The cell parameter and the Fe magnetic moments versus temperature are determined. The misunderstanding on interstitial site is clarified. The magnetovolume effect on the Curie temperature is explained by combination of the structural and magnetic properties. The advantages and drawbacks of each type of element insertion are discussed.

Low temperature frequency dependence of the electron spin resonance absorption in heavily phosphorus-doped silicon

1970 ◽  
Vol 48 (24) ◽  
pp. 2930-2936 ◽  
Author(s):  
F. T. Hedgcock ◽  
T. W. Raudorf
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Magnetic Moments ◽  
Charge Carriers ◽  
Mobile Charge ◽  
Local Moments ◽  
Spin Resonance ◽  
Doped Silicon ◽  
Pauli Paramagnetism ◽  
Phosphorus Doped

Electron spin resonance (ESR) measurements have been made on a phosphorus-doped silicon specimen (n = 1.38 × 1019/cc) in the liquid helium temperature range. A single line with a g factor of approximately 2 was observed for resonant magnetic fields of 540, 3230, and 12 590 G at 1517, 9010, and 35 200 MHz respectively. The experimentally determined magnetization is compared with the magnetizations expected from the following sources: (a) un-ionized charge carriers or local magnetic moments obeying a Curie law, (b) mobile carriers experiencing an exchange interaction with local magnetic moments, and (c) mobile charge carriers showing only Pauli paramagnetism. The magnetization derived from the ESR data exhibits a linear dependence with magnetic field and no temperature dependence. This is consistent with the Pauli paramagnetism expected for mobile charge carriers in the absence of any interaction with local moments.

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