H. C. Xuan

Publications (18)52.38 Total impact

• Article: Study of uniaxial magnetism and enhanced magnetostriction in magnetic-annealed polycrystalline CoFe2O4

  Y. X. Zheng, Q. Q. Cao, C. L. Zhang, H. C. Xuan, L. Y. Wang, D. H. Wang, Y. W. Du
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  ABSTRACT: Magnetic and magnetostrictive properties of magnetic-annealed polycrystalline CoFe2O4 were investigated. The magnetic hysteresis loops showed obvious uniaxiality with an induced easy direction parallel to the annealing field. Magnetic force microscopy study revealed that the domains were fixed by magnetic annealing. The uniaxial behavior was also observed in the magnetostrictive measurement, which showed a significantly enhanced magnetostriction of − 273 PPM when the external field was applied perpendicular to the annealing field direction. A physical mechanism for the effect of magnetic annealing on polycrystalline CoFe2O4 is developed, in which the induced uniaxiality is ascribed to the realignment of easy axes in polycrystals. The uniaxial behavior of magnetism and enhanced magnetostriction could be well explained by this model.
  Journal of Applied Physics 08/2011; 110(4):043908-043908-7. · 2.17 Impact Factor
• Article: Electric field control of magnetism without magnetic bias field in the Ni/Pb(Mg1/3Nb2/3)O3-PbTiO3/Ni composite

  H. C. Xuan, L. Y. Wang, Y. X. Zheng, Y. L. Li, Q. Q. Cao, S. Y. Chen, D. H. Wang, Z. G. Huang, Y. W. Du
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  ABSTRACT: This paper reports on the electric field control of magnetism without magnetic bias field in a Ni/Pb(Mg1/3Nb2/3)O3-PbTiO3/Ni composite prepared by electrochemical deposition. The converse magnetoelectric effect, which was measured by an induction method, shows a peak value of 0.45 G/V at the resonance frequency of 102 kHz. Without magnetic bias field, the magnetization of the Ni layers can be controlled by an applied dc electric field in a reversible and reproducible way and shows an analogous on-off behavior with the electric field switching on and off alternatively.
  Applied Physics Letters 07/2011; 99(3):032509-032509-3. · 3.84 Impact Factor
• Article: Large and highly reversible magnetic field-induced strains in textured Co1−xNixMnSi alloys at room temperature

  C L Zhang, Y X Zheng, H C Xuan, S C Ma, Q Q Cao, D H Wang, Y W Du
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  ABSTRACT: The metamagnetic transition and magnetoelastic properties are investigated in transition-metal-based Co1−xNixMnSi (0 < x < 0.03) alloys. Large low-field magnetostrains are observed in the Ni-doped CoMnSi alloys. Compared with some other metamagnetic materials with large magnetic field-induced strains, the present alloys show highly reversible magnetoelastic behaviour and have almost constant strain outputs around room temperature. These observations may shed light on developing transition-metal-based magnetostrictive materials.
  Journal of Physics D Applied Physics 03/2011; 44(13):135003. · 2.54 Impact Factor
• Article: The martensitic transformation, magnetocaloric effect, and magnetoresistance in high-Mn content Mn47+xNi43−xSn10 ferromagnetic shape memory alloys

  H. C. Xuan, Y. X. Zheng, S. C. Ma, Q. Q. Cao, D. H. Wang, Y. W. Du
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  ABSTRACT: A series of high-Mn content Mn47+xNi43−xSn10 (x = 0, 1, 2, 3, 4, and 5) ferromagnetic shape memory alloys were prepared by arc melting method. The martensitic transformation were observed in these alloys, even the content of Mn is higher than 50 at. %. The phase transition temperature of these alloys can be adjusted by tuning the compositions of Ni and Mn. Large positive magnetic entropy change and negative magnetoresistance which originate from the magnetic-field-induced martensitic transformation are obtained in these alloys.
  Journal of Applied Physics 11/2010; 108(10):103920-103920-4. · 2.17 Impact Factor
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  Article: Investigation of the intermediate phase and magnetocaloric properties in high-pressure annealing Ni–Mn–Co–Sn alloy

  S. C. Ma, H. C. Xuan, C. L. Zhang, L. Y. Wang, Q. Q. Cao, D. H. Wang, Y. W. Du
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  ABSTRACT: The Ni–Mn–Co–Sn alloy is prepared by high-pressure annealing method. Besides the enhanced martensitic transformation temperature and the Curie temperature of austenite, an intermediate phase above the martensitic transformation is observed in this alloy. As a result, two successive magnetic entropy changes with the same sign are obtained around room-temperature, corresponding to the martensitic transformation and intermediate phase transition, respectively. The origin of the intermediate phase for high-pressure annealing Ni–Mn–Co–Sn alloy is discussed.
  Applied Physics Letters 08/2010; 97(5):052506-052506-3. · 3.84 Impact Factor
• Article: Large exchange bias field in the Ni–Mn–Sn Heusler alloys with high content of Mn

  H. C. Xuan, Q. Q. Cao, C. L. Zhang, S. C. Ma, S. Y. Chen, D. H. Wang, Y. W. Du
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  ABSTRACT: The exchange bias properties have been investigated in bulk Mn ₅₀ Ni _{40- x} Sn _{10+ x} ( x =0 , 0.5, and 1) Heusler alloys with high content of Mn, in which the largest exchange bias field is up to 910 Oe for Mn ₅₀ Ni ₄₀ Sn ₁₀ alloy. In these alloys, the excess Mn atoms would occupy not only the Sn sites but also the Ni sites, and the moments of Mn on Sn or Ni sites are coupled antiferromagnetically to those on the regular Mn sites, respectively. The origin of this considerably large exchange bias field has been discussed.
  Applied Physics Letters 06/2010; · 3.84 Impact Factor
• Article: Large magnetic entropy changes in Gd–Co amorphous ribbons

  C. L. Zhang, D. H. Wang, Z. D. Han, H. C. Xuan, B. X. Gu, Y. W. Du
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  ABSTRACT: A series of magnetic amorphous ribbons with different Gd/Co ratios was prepared by melt-spun method. With the decrease in Gd/Co ratio, Curie temperatures increase gradually from 166 to 193 K. The maximum values of magnetic entropy changes under a magnetic field of 10 kOe are -3.1 , -3.0 , -2.9 , and -2.8 J / kg   K for Gd ₇₁ Co ₂₉ , Gd ₆₈ Co ₃₂ , Gd ₆₅ Co ₃₅ , and Gd ₆₂ Co ₃₈ samples, respectively. The approximately constant peak values of ΔS_M at different working temperatures indicate that they are advantageous for an Ericsson refrigeration cycle. In addition, these samples have large resistivity and greatly reduced magnetic hysteresis losses, which could increase the refrigeration efficiency. These advantages make the Gd–Co amorphous ribbons good candidates for the practical magnetic refrigeration.
  Journal of Applied Physics 02/2009; · 2.17 Impact Factor
• Article: Large magnetic entropy change and broad working temperature span in CoMnSi0.88Ge0.12 alloy

  C L Zhang, D H Wang, Q Q Cao, Z D Han, H C Xuan, Y W Du
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  ABSTRACT: CoMnSi0.88Ge0.12 alloy was prepared using an optimized annealing routine. The metamagnetic transition between antiferromagnetism and ferromagnetism can be observed in this alloy by either increasing the temperature or applying a magnetic field. The metamagnetic transition temperature is very sensitive to the applied field. Owing to the low metamagnetic critical field and large variation in magnetization, large and positive magnetic entropy changes as well as broad working temperature spans are obtained in this metamagnetic system.
  Journal of Physics D Applied Physics 12/2008; 42(1):015007. · 2.54 Impact Factor
• Article: Effect of annealing on the martensitic transformation and magnetoresistance in Ni–Mn–Sn ribbons

  H C Xuan, Y Deng, D H Wang, C L Zhang, Z D Han, Y W Du
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  ABSTRACT: Ni44.1Mn44.2Sn11.7 ribbons were prepared by melt spinning. After heat treatment, the martensitic transformation (MT) temperature increases obviously in the annealed ribbons. Large magnetoresistance (MR) was observed in these ribbons. Under the field of 50 kOe, the maximum values of negative MR were 22% for melt-spun ribbons at 240 K and 38% for annealed ribbons at 268 K, respectively. The annealing effect on MT and MR, together with the origin of the large MR, has been discussed in this paper.
  Journal of Physics D Applied Physics 10/2008; 41(21):215002. · 2.54 Impact Factor
• Article: The phase transitions, magnetocaloric effect, and magnetoresistance in Co doped Ni–Mn–Sb ferromagnetic shape memory alloys

  Z. D. Han, D. H. Wang, C. L. Zhang, H. C. Xuan, J. R. Zhang, B. X. Gu, Y. W. Du
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  ABSTRACT: The phase transitions, magnetocaloric effect, and magnetoresistance in Ni _50-x Co _x Mn ₃₉ Sb ₁₁ (x=0–11) ferromagnetic shape memory alloys were investigated. The temperatures of martensitic transformation and magnetic transition in austenitic phase depend strongly on the Co concentration, while the magnetic transition temperature in martensitic phase shows small dependence on alloy composition. For 7≤x≤9 , the martensitic transformation is accompanied by a sudden change in magnetization. Large positive magnetic entropy changes and negative magnetoresistance near room temperature, which originate from the magnetic-field-induced transformation from the weak-magnetic high-resistance martensitic phase to the ferromagnetic low-resistance parent phase, are observed in these alloys. Our results indicate the potential application of Ni _50-x Co _x Mn ₃₉ Sb ₁₁ alloys in magnetic refrigeration and magnetic sensors.
  Journal of Applied Physics 10/2008; · 2.17 Impact Factor
• Article: Magnetostructural phase transition and magnetocaloric effect in off-stoichiometric Mn1.9−xNixGe alloys

  C. L. Zhang, D. H. Wang, Q. Q. Cao, Z. D. Han, H. C. Xuan, Y. W. Du
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  ABSTRACT: Phase transitions and magnetic entropy changes are studied in Mn1.9−xNixGe (x = 0.85, 0.855) alloys. In these off-stoichiometric alloys, the crystallographic transition temperature decreases remarkably due to the deficiency of transition-metal atoms, and, consequently, a magnetostructural transition from the antiferromagnetic TiNiSi-type structure to the ferromagnetic Ni2In-type structure is observed. Owing to the abrupt change in magnetization, large magnetic entropy changes are obtained. The effect of transition-metal vacancies on the phase transition temperature is discussed.
  Applied Physics Letters 09/2008; 93(12):122505-122505-3. · 3.84 Impact Factor
• Article: Effect of annealing on the martensitic transformation and magnetocaloric effect in Ni44.1Mn44.2Sn11.7 ribbons

  H. C. Xuan, K. X. Xie, D. H. Wang, Z. D. Han, C. L. Zhang, B. X. Gu, Y. W. Du
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  ABSTRACT: The Ni44.1Mn44.2Sn11.7 ribbons were prepared by melt spinning. A single-phase austenite with L21 structure was confirmed in the melt-spun ribbons at room temperature. After the heat treatment, the martensitic transformation temperature increases obviously in the annealed ribbons. This method may be an effective way to tune the characteristic temperatures in the ferromagnetic shape memory alloys. Giant magnetic entropy changes are observed in the annealed ribbons. The peak values at 10 kOe are 32.1 and 20.1 J/kg K, for the ribbons annealed at 1123 and 1173 K, respectively.
  Applied Physics Letters 06/2008; 92(24):242506-242506-3. · 3.84 Impact Factor
• Article: Boron’s effect on martensitic transformation and magnetocaloric effect in Ni43Mn46Sn11Bx alloys

  H. C. Xuan, D. H. Wang, C. L. Zhang, Z. D. Han, B. X. Gu, Y. W. Du
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  ABSTRACT: The most used method for changing the martensitic transformation temperatures in the ferromagnetic shape memory alloys is tuning the valence election concentration e/a. In this paper, we report an alternative way, i.e., introducing few interstitial boron atoms in Ni43Mn46Sn11 alloy. The experimental results show that the martensitic transformation temperatures increase with the increasing boron content remarkably and large magnetic entropy changes can be obtained in these alloys. A possible origin of the enhanced martensitic transformation temperatures and large magnetic entropy changes is discussed in this paper.
  Applied Physics Letters 03/2008; 92(10):102503-102503-3. · 3.84 Impact Factor
• Article: Large magnetic entropy changes and magnetoresistance in Ni45Mn42Cr2Sn11 alloy

  D. H. Wang, C. L. Zhang, Z. D. Han, H. C. Xuan, B. X. Gu, Y. W. Du
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  ABSTRACT: The magnetic entropy changes and magnetoresistance were studied in Ni45Mn42Cr2Sn11 ferromagnetic shape memory alloy near the martensitic transition temperature. The substitution of Mn by Cr leads to the rapid decrease of the martensitic transition temperature. A large magnetic entropy change, ΔSM, of 15 J/kg K in a magnetic field of 10 kOe and a large negative MR of 45% in a magnetic field up to 50 kOe were observed in this alloy. The temperature and magnetic field induced martensitic transition should be the origin of large ΔSM and MR in Ni45Mn42Cr2Sn11 ferromagnetic shape memory alloy.
  Journal of Applied Physics 01/2008; 103(3):033901-033901-4. · 2.17 Impact Factor
• Article: Giant low-field magnetic entropy changes in Ni45Mn44−xCrxSn11 ferromagnetic shape memory alloys

  C L Zhang, W Q Zou, H C Xuan, Z D Han, D H Wang, B X Gu, Y W Du
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  ABSTRACT: A series of Ni45Mn44−xCrxSn11 (x = 0, 1, 2) ferromagnetic shape memory alloys were prepared. With slight doping of Cr, the martensitic transition temperatures decrease rapidly. The magnetic entropy changes at a low magnetic field were investigated in these alloys. The maximum value of ΔSM is 23.4 J kg−1 K−1, which was observed in Ni45Mn43CrSn11 alloys. The origin of the magnetic entropy changes in these alloys has been discussed. The giant low-field magnetic entropy changes and low cost make Ni45Mn44−xCrxSn11 alloys a promising candidate for magnetic refrigeration.
  Journal of Physics D Applied Physics 11/2007; 40(23):7287. · 2.54 Impact Factor
• Article: The study of low-field positive and negative magnetic entropy changes in Ni43Mn46-xCuxSn11 alloys

  D. H. Wang, C. L. Zhang, H. C. Xuan, Z. D. Han, J. R. Zhang, S. L. Tang, B. X. Gu, Y. W. Du
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  ABSTRACT: A series of Ni ₄₃ Mn _46-x Cu _x Sn ₁₁ ( x=1 , 2, and 3) alloys was prepared by the arc melting method. The martensitic transition shifts to a higher temperature with increasing Cu concentration. The isothermal magnetization curves around the martensitic transition temperature show a typical metamagnetic behavior. Under a low applied magnetic field of 10 kOe , positive values of magnetic entropy change around the martensitic transition temperature are 14.1, 18.0, and 15.8 J / kg K for x=1 , 2, and 3, respectively. While in the vicinity of the Curie temperature of the austenitic phase, these negative values are 1.1, 1.0, and 0.9 J / kg K for x=1 , 2, and 3, respectively. The origin of the large entropy changes and the potential application for Ni ₄₃ Mn _46-x Cu _x Sn ₁₁ alloys as a working substance for magnetic refrigeration are discussed.
  Journal of Applied Physics 08/2007; · 2.17 Impact Factor
• Article: Low-field inverse magnetocaloric effect in Ni50-xMn39+xSn11 Heusler alloys

  Z. D. Han, D. H. Wang, C. L. Zhang, H. C. Xuan, B. X. Gu, Y. W. Du
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  ABSTRACT: The low-field magnetic entropy changes in Ni _50-x Mn _39+x Sn ₁₁ alloys ( x=5 , 6, and 7) were investigated. The martensitic transition shifts to lower temperature with the increase of Mn concentration. Under an applied magnetic field of 10 kOe , the magnetic entropy changes are 6.8, 10.1, and 10.4 J / kg K , for x=5 , 6, and 7, respectively. The large entropy change in Ni _50-x Mn _39+x Sn ₁₁ can be attributed to the sharp magnetization change associated with the martensitic transition from a ferromagnetic parent phase to a weak-magnetic martensitic phase. The large low-field magnetic entropy change and low cost suggest Ni _50-x Mn _39+x Sn ₁₁ alloy as the promising magnetic refrigerant.
  Applied Physics Letters 02/2007; · 3.84 Impact Factor
• Article: Magnetic and magnetocaloric properties in melt-spun and annealed Ni42.7Mn40.8Co5.2Sn11.3 ribbons

  S.C. Ma, Q.Q. Cao, H.C. Xuan, C.L. Zhang, L.J. Shen, D.H. Wang, Y.W. Du
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  ABSTRACT: The Ni42.7Mn40.8Co5.2Sn11.3 ribbons were prepared by melt spinning. After heat treatment, the martensitic transformation temperature and Curie temperature of austenite of the annealed ribbons increased remarkably. Inverse and direct magnetocaloric properties were investigated in the melt-spun and annealed ribbons. The effective refrigerant capacities for these ribbons were discussed in this paper.Research highlightsIn this paper, the Ni42.7Mn40.8Co5.2Sn11.3 ribbons were prepared by melt spinning and the magnetic and magnetocaloric properties for the melt-spun and annealed ribbons were investigated. After heat treatment, the martensitic transformation (MT) temperature and Curie temperature of austenite increased remarkably. Enhanced magnetization and obvious metamagnetic behavior are also observed in the annealed ribbons. Large near-room-temperature magnetocaloric effects can be obtained in these ribbons. The values of isothermal magnetic entropy change ΔSM around MT and of the annealed ribbons are larger than those of melt-spun ones. However, the effective refrigerant capacities RCeff around MT retains almost unchanged for these ribbons, owing to the large hysteretic losses associated with the field-induced metamagnetic transition in the annealed ribbons. Around , RCeff increases notably after heat treatment and is much larger than that around MT.
  Journal of Alloys and Compounds 509(4):1111-1114. · 2.29 Impact Factor