Specific Heat and Entropy of RNi2 (R: Rare Earth Heavy Metals) in Magnetic Field

Tomokiyo, Akihisa; Yayama, Hideki; Wakabayashi, Hidetsugu; Kuzuhara, T.; Hashimoto, Toshimasa; Sahashi, M.; Inomata, K.

doi:10.1007/978-1-4613-9871-4_35

Cited by 29 publications

(33 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Manifestation of diverse magnetic properties by the rare earth (R) transition metal (TM) intermetallic compounds in general and the occurrence of giant MCE in materials such as Gd 5 (Si,Ge) 4 in particular have made R-TM compounds as the natural probe for the fundamental studies as well as for applications based on MCE [1,[7][8][9]. Among the various R-TM intermetallics, RCo 2 (R=Er, Ho and Dy) compounds are known to exhibit considerable MCE due to the first order transition at their ordering temperature (T C ) [8].…”

Section: Introductionmentioning

confidence: 99%

Role of Fe substitution on the anomalous magnetocaloric and magnetoresistance behaviour in Tb(Ni_1−xFe_x)₂compounds

Singh¹,

Суреш²,

Rana³

et al. 2006

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

Abstract. We report the magnetic, magnetocaloric and magnetoresistance results obtained in Tb(Ni 1-x Fe x ) 2 compounds with x=0, 0.025 and 0.05. Fe substitution leads to an increase in the ordering temperature from 36 K for x=0 to 124 K for x=0.05. Contrary to a single sharp MCE peak seen in TbNi 2 , the MCE peaks of the Fe substituted compounds are quite broad. We attribute the anomalous MCE behavior to the randomization of the Tb moments brought about by the Fe substitution. Magnetic and magnetoresistance results seem to corroborate this proposition. The present study also shows that the anomalous magnetocaloric and magnetoresistance behavior seen in the present compounds is similar to that of Ho(Ni,Fe) 2 compounds.

show abstract

Section: Introductionmentioning

confidence: 99%

Role of Fe substitution on the anomalous magnetocaloric and magnetoresistance behaviour in Tb(Ni_1−xFe_x)₂compounds

Singh¹,

Суреш²,

Rana³

et al. 2006

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

show abstract

“…15 Experimental investigations carried out in HoNi 2 are in close agreement with the theoretically predicted results. 16,17 These reports have motivated us to focus our studies on the HoNi 2 -based system. With the aim of achieving a composite material with distributed T C , we have partially substituted nominal concentrations of Fe for Ni in HoNi 2 which is intended to increase the magnetic ordering temperature.…”

Section: Introductionmentioning

confidence: 99%

Anomalous magnetocaloric effect and magnetoresistance inHo(Ni,Fe)2compounds

et al. 2005

View full text Add to dashboard Cite

Magnetic, magnetocaloric, and magnetoresistance studies have been carried out on polycrystalline samples of Laves phase compounds Ho͑Ni 1−x Fe x ͒ 2 ͓x = 0, 0.05, and 0.1͔. The magnetocaloric effect in HoNi 2 is found to be maximum near the ordering temperature with values of 7 J mol −1 K −1 and 10.1 K for the isothermal magnetic entropy change and the adiabatic temperature change, respectively, for a field of 50 kOe. With Fe substitution, the temperature variation of magnetocaloric effect shows an additional peak at low temperatures, which is much more pronounced than the peak at the ordering temperature. The origin of the low temperature peak is attributed to the field-induced metamagnetic transition. The magnetoresistance data also seem to support the occurrence of the metamagnetic transition.

show abstract

“…M͑T͒ curve on heating at 5 kOe after ZFC from 300 K showed a cuspid between 12 and 27 K, and the expected AFM-to-paramagnetic transition at Ӎ130 K, in agreement with previously reported results. 15,17 A second ZFC curve, recorded on heating at 5 kOe after applying a field of 50 kOe during a few seconds at 4 K, shows a strong decrease at ϳ25 K and matches the first ZFC curve above ϳ30 K. Isothermal magnetization curves were measured while increasing and decreasing the field after ZFC from above 130 K, at temperatures T = 4, 6,8,10,12,14,16,18,20,25,30,35,40, and 45 K. From 4 to 20 K, the magnetization curves while increasing the field showed the expected irreversible transition between AFM and FM phases, 15,17 the sample remaining in the FM phase after the field was further reduced down to zero. The presence of a 22% FM component in the virgin sample 16,22 was estimated from the saturation in the magnetization curve at 4 K, observed before the irreversible transition takes place.…”

mentioning

confidence: 68%

“…12 In order to enhance MCE at low temperatures, materials with a second-order phase transition have been investigated, such as ErAl 2 ͑Ref. 13͒ and ErNi 2 , 14 but as far as we know, MCE associated with a first-order phase transition below 20 K has not been reported.…”

mentioning

confidence: 99%

“…26 Calorimetric curves shown in Fig. 1 were obtained after ZFC the sample from a temperature well above 130 K ͑which corresponds to the Néel temperature of the material͒ down to a given temperature T. This procedure was carried out at temperatures T = 4, 6,8,10,12,14,16,18,20,25,30,35,40, and 45 K. Calorimetric curves for 4-16 K are displayed in Fig. 1͑a͒.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Giant heat dissipation at the low-temperature reversible-irreversible transition inGd5Ge4

2005

View full text Add to dashboard Cite

The heat exchanged at the low-temperature first-order magnetostructural transition is directly measured in Gd 5 Ge 4 . Results show that the origin and the temperature dependence of the heat exchanged varies with the reversible/irreversible character of the first-order transition. In the reversible regime, the heat exchanged by the sample is mostly due to the latent heat at the transition and decreases with decreasing temperature, while in the irreversible regime, the heat is irreversibly dissipated and increases strongly with decreasing temperature, reaching a value of 237 J / kg at 4 K. 12 In order to enhance MCE at low temperatures, materials with a second-order phase transition have been investigated, such as ErAl 2 ͑Ref. 13͒ and ErNi 2 , 14 but as far as we know, MCE associated with a first-order phase transition below 20 K has not been reported.Gd 5 ͑Si x Ge 1−x ͒ 4 alloys have been extensively studied since the discovery of giant MCE in x ഛ 0.5 compounds. 3 Ge-rich compounds ͑x ഛ 0.2͒ present a first-order structural transition ranging from ϳ20 K ͑x =0͒ to ϳ120 K ͑x = 0.2͒, accompanied by a change in the magnetic ordering between antiferromagnetic ͑AFM͒ and ferromagnetic ͑FM͒ state, 3-5 which gives rise to a large entropy change. In particular, the unusual magnetic behavior shown by the end-compound Gd 5 Ge 4 at low temperatures has lately attracted a lot of interest. [15][16][17][18][19][20][21][22][23][24] In this alloy, the nature of the AFM ordering related to the high-temperature phase is complex, with competing AFM ͑between layers͒ and FM interactions ͑within layers͒. 5,[15][16][17][18] Moreover, due to this anisotropy in the exchange interactions, the magnetic ordering remains AFM without undergoing the structural transition after zero-field-cooling ͑ZFC͒ down to ϳ2 K. 15,19 The application of a certain magnetic field, whose value depends on the temperature, induces the first-order AFM-to-FM transition, which is irreversible at temperatures below ϳ10 K, partially reversible from ϳ10 to ϳ20 K and fully reversible above ϳ20 K ͑Refs. 15, 17, 20, and 21͒ as in the rest of Ge-rich compounds. The irreversibility of the transition might be due to a hindrance of the kinetics of the reversed AFM-FM transition, which at sufficiently low temperatures and high fields becomes arrested ͑i.e., structural relaxation time is larger than experimental time scales͒. 21,24 In this work, a study of the heat absorbed or released at the low-temperature irreversible and reversible first-order field-induced phase transitions is carried out in Gd 5 Ge 4 . Results show that the origin and the temperature dependence of the exchanged heat varies with the reversible/irreversible character of the first-order transition. In detail, the heat exchanged by the sample in the reversible regime is majorly due to the latent heat at the magnetostructural transition, while the heat dissipation associated with the magnetic work is much smaller. In contrast, in the irreversible regime, giant heat dissipation much larger than the latent heat...

show abstract

Specific Heat and Entropy of RNi2 (R: Rare Earth Heavy Metals) in Magnetic Field

Cited by 29 publications

References 5 publications

Role of Fe substitution on the anomalous magnetocaloric and magnetoresistance behaviour in Tb(Ni_1−xFe_x)₂compounds

Role of Fe substitution on the anomalous magnetocaloric and magnetoresistance behaviour in Tb(Ni_1−xFe_x)₂compounds

Anomalous magnetocaloric effect and magnetoresistance inHo(Ni,Fe)2compounds

Giant heat dissipation at the low-temperature reversible-irreversible transition inGd5Ge4

Contact Info

Product

Resources

About

Specific Heat and Entropy of RNi2 (R: Rare Earth Heavy Metals) in Magnetic Field

Cited by 29 publications

References 5 publications

Role of Fe substitution on the anomalous magnetocaloric and magnetoresistance behaviour in Tb(Ni1−xFex)2compounds

Role of Fe substitution on the anomalous magnetocaloric and magnetoresistance behaviour in Tb(Ni1−xFex)2compounds

Anomalous magnetocaloric effect and magnetoresistance inHo(Ni,Fe)2compounds

Giant heat dissipation at the low-temperature reversible-irreversible transition inGd5Ge4

Contact Info

Product

Resources

About

Role of Fe substitution on the anomalous magnetocaloric and magnetoresistance behaviour in Tb(Ni_1−xFe_x)₂compounds

Role of Fe substitution on the anomalous magnetocaloric and magnetoresistance behaviour in Tb(Ni_1−xFe_x)₂compounds