Low temperature magnetic hardness of melt spun Fe-Zr amorphous alloys

Read, D.A.; Moyo, T.; Hallam, G.C.

doi:10.1016/0304-8853(84)90254-3

Cited by 59 publications

(31 citation statements)

References 10 publications

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“…(ii) There is a broad minimum in the resistance at a particular temperature (T min ). T min is very close to T C [18] of the respective compositions. (iii) T min is observed at about 245 and 230 K for 9.5 and 8.5 at% of Zr, respectively.…”

Section: Resultsmentioning

confidence: 71%

Temperature Dependence of the Electrical Resistivity of a-FeZr Alloys

Srinivas

1998

phys. stat. sol. (b)

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The temperature dependence of electrical resistivity of a-Fe 100±x Zr x alloys (x = 8.5 and 9.5) is measured in the temperature range 5 to 300 K. Our observations indicate some correlations between the magnetic and electrical resistivity behavior near the transition region. The resistivity data have been analyzed in the light of both magnetic and nonmagnetic scattering models to quantify the contributions from these scattering processes. From the quantitative analysis it is found that the magnetic contribution is noticeable around the transition temperature and the nonmagnetic contribution is present in the complete temperature range of the present study.

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Section: Resultsmentioning

confidence: 71%

Temperature Dependence of the Electrical Resistivity of a-FeZr Alloys

Srinivas

1998

phys. stat. sol. (b)

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“…Hydrogen doping of Fe-rich amorphous Fe-Zr alloys decreases very rapidly the coercive field, which are similarly explained by the introduced lattice distortions [21]. Both versions of the model result in an exponential increase of the coercivity, H c , with decreasing temperature, which is related to the upper tail of the assumed Gaussian distribution for the Fe concentration [4].…”

Section: Introductionmentioning

confidence: 85%

“…(3) Fe 93 Zr 7 transforms directly from the FM into the SG state at the SG temperature (T g ). Another magnetic anomaly in these systems is the very rapidly increasing magnetic hardness on cooling as well as on decreasing Zr content [4], as deduced from coercivity measurements. Also, irreversible magnetization changes are observed below T f and T g .…”

Section: Introductionmentioning

confidence: 93%

“…The origin of the peculiar magnetic properties [1][2][3][4][5] of Fe-rich Fe-transition metal (TM) (T M = Zr, Ti, Hf, Nd, Sc, La, Ce) metallic glasses at low temperatures has been a challenge for decades. Perhaps the most studied of these glasses are the amorphous Fe-Zr alloys because in a very narrow composition range (Fe 100−x Zr x ,7 x 12), three different types of magnetic behavior can be observed.…”

Section: Introductionmentioning

confidence: 99%

“…In the model of Read et al and Moyo [4,[14][15][16], the main effort is put on, explaining quantitatively the sharp temperature and composition dependence of the magnetic hardness. In the early form of the model [4,14,15], the presence of AF clusters dispersed in an FM matrix was assumed, and the magnetic hardness was attributed to pinning to these clusters, considered as nonmagnetic inclusions below their Néel temperatures. Thus, the coercivity will be proportional to the volume fraction of the AF clusters.…”

Section: Introductionmentioning

confidence: 99%

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Influence of the critical Fe atomic volume on the magnetism of Fe-rich metallic glasses evidenced by pressure-dependent measurements

et al. 2016

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Despite the intensive studies for decades, it is still not well understood how qualitatively different magnetic behaviors can occur in a narrow composition range for the Fe-rich Fe-transition metal (TM) amorphous alloys. In this study of amorphous Fe 100−x Zr x (x = 7, 9, 12) metallic glasses, normal ferromagnetism (FM) is found at 12 % Zr where only the FM-paramagnetic (PM) transition is observed at the Curie temperature, T C . In contrast, spin-glass (SG)-PM transition at a temperature, T g , called SG temperature, is only observed at 7 % Zr, while in the transient re-entrant composition range (x = 8−11), an SG-FM transition at a temperature, T f , called spin-freezing temperature, is also observed at low temperature besides the normal FM-PM transition at T C . In order to understand this unusual behavior, a detailed characterization of pressure (atomic volume), composition, and temperature dependence of the magnetic properties is coupled with high pressure synchrotron x-ray diffraction determination of the pressure dependence of the atomic volume. The results on Fe 100−x Zr x (x = 7, 9, 12) are compared to those obtained for the FM Co 91 Zr 9 metallic glass not showing any kind of anomalous magnetic properties. It is confirmed that the unusual behavior is caused by a granularlike magnetic structure where weakly coupled magnetic clusters are embedded into a FM bulk matrix. Since the mechanism of the magnetization reversal was found to be of the curling type rather than homogeneous rotation, the energy barrier determining the blocking temperature of the clusters is calculated as AR, where A is the exchange constant and R is the cluster size, in contrast to the usual characterization of the energy barrier by KV where K is the anisotropy energy and V is the cluster volume. The volume fraction of the FM part is a fast changing function of the bulk composition: Almost 100% FM fraction is found at 12 % of Zr while no trace of real FM is observed at 7 at % Zr. The driving force of this surprising magnetic character is the atomic volume: The lower the Zr content, the higher is the fraction of Fe atoms with compressed atomic volume having low magnetic moment. The percolation of their network separates the clusters from the FM bulk. The complex magnetic behavior of the Fe-rich Fe-Zr amorphous system at low temperatures can thus be interpreted with the only assumption of a cluster-size distribution and a weak coupling of the clusters to the FM matrix. The introduction of this coupling is able to explain the opposite pressure dependence of T g and T f . The threshold atomic volume in the low magnetic moment regions is found to be comparable to the atomic volume characteristic to the low-spin limit of the face-centered-cubic Fe alloys. The extensive literature results on the anomalous magnetism for various Fe-rich Fe-TM amorphous alloys and especially for the Fe-rich Fe-Zr glassy system are also found to be in agreement with this granular magnetic behavior.

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An ac Susceptibility Study of Mn Substituted Amorphous FeZr Alloys

Perumal¹,

Srinivas²,

Dhar³

et al. 2000

phys. stat. sol. (a)

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The temperature dependence of the ac susceptibility of amorphous Fe 90Àx Mn x Zr 10 (x 0, 4, 8) has been measured at different ac fields in the frequency range of 80 Hz to 1 kHz. All the compositions of the present study exhibit a double magnetic transition below room temperature. It is found that the Curie temperature T C decreases while the spin-glass transition temperature T f increases as Mn concentration increases from 0 to 8 at%. The values of T C and critical exponent associated with the magnetic susceptibility were extracted from ac susceptibility measurements. The critical exponent is in close agreement with the value predicted by the three-dimensional Heisenberg model. The results obtained here can be explained on the basis of competing exchange interactions below the magnetic ordering temperature.

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Low temperature magnetic hardness of melt spun Fe-Zr amorphous alloys

Cited by 59 publications

References 10 publications

Temperature Dependence of the Electrical Resistivity of a-FeZr Alloys

Temperature Dependence of the Electrical Resistivity of a-FeZr Alloys

Influence of the critical Fe atomic volume on the magnetism of Fe-rich metallic glasses evidenced by pressure-dependent measurements

An ac Susceptibility Study of Mn Substituted Amorphous FeZr Alloys

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