The Hall coefficient, RH, of the triclinic Al73Mn27 and Taylor-phase Al73Mn27xPdx (x = 0, 2, 4 and 6) complex metallic alloys has been measured from 90 to 400 K. The Hall coefficients of all the samples are positive and they decrease strongly with the increase of temperature, T. For the separation of the normal, R0, and anomalous, RS, Hall coefficient the results for the paramagnetic susceptibility,χ(T), and electrical resistivity, ρ(T), have been used. The well defined linearity of the RH vs. χ(T)·ρ2(T) plots confirms the assumption that in these materials RH is dominated by spin-orbit interaction. The values deduced from the RH vs. χ and RH vs. χ·ρ2 plots in T­AlMnPd phases, fall between –2 × 10–10 m3 C–1
and 0 for R0, and are about 5 × 10–7 m3 C–1 for RS. The values deduced from the RH vs. χ·ρ2 plots in the triclinic Al73Mn27 alloy are about –15 × 10–10 m3 C–1 for R0, and about 1.5 × 10–5 m3 C–1 for RS.</p

Denis Stanić

Janez Dolinšek

Jovica Ivkov

Marc Heggen

Michael Feuerbacher

Zvonko Jagličić

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 * Presented at the EU Workshop "Frontiers in Complex Metallic Alloys", Zagreb, October 2008. Dedicated to Professor Boran Leontić on the occasion of his 80th birthday. ** Author to whom correspondence should be addressed. (E-mail: ivkov@ifs.hr) CROATICA CHEMICA ACTA CCACAA, ISSN 0011-1643, e-ISSN 1334-417X Croat. Chem. Acta 83 (1) (2010) 11–14.  CCA-3382  Original Scientific Paper Hall Effect of the Triclinic Al73Mn27 and T-Al73Mn27–xPdx (0 ≤ x ≤ 6) Complex Metallic Alloys* Jovica Ivkov,a,** Denis Stanić,a Zvonko Jagličić,b Janez Dolinšek,c Marc Heggen,d and Michael Feuerbacherd  aLaboratory for the Physics of Transport Phenomena, Institute of Physics, Bijenička c. 46, P. O. Box 304,  HR-10001 Zagreb, Croatia bInstitute of Mathematics, Physics and Mechanics & Faculty of Civil and Geodetic Engineering,  University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia cJožef  Stefan Institute, University of Ljubljana, Jamova 39, SI-1000 Ljubljana, Slovenia dInstitut für Festkörperforschung, Forschungszentrum Jülich, Jülich D-52425, Germany RECEIVED JULY 23, 2008; ACCEPTED SEPTEMBER 4, 2009   Abstract. The Hall coefficient, RH, of the triclinic Al73Mn27 and Taylor-phase Al73Mn27–xPdx (x = 0, 2, 4 and 6) complex metallic alloys has been measured from 90 to 400 K. The Hall coefficients of all the sam-ples are positive and they decrease strongly with the increase of temperature, T. For the separation of the normal, R0, and anomalous, RS, Hall coefficient the results for the paramagnetic susceptibility,  (T ), and electrical resistivity, ρ(T ), have been used. The well defined linearity of the RH vs. χ (T ) ·ρ2(T ) plots con-firms the assumption that in these materials RH is dominated by spin-orbit interaction. The values deduced from the RH vs. χ and RH vs. χ ·ρ2 plots in T-AlMnPd phases, fall between –2 × 10–10 m3 C–1 and 0 for R0, and are about 5 × 10–7 m3 C–1 for RS. The values deduced from the RH vs. χ ·ρ2 plots in the triclinic Al73Mn27 alloy are about –15 × 10–10 m3 C–1 for R0, and about 1.5 × 10–5 m3 C–1 for RS.  Keywords: complex metallic alloys, Hall effect  INTRODUCTION Al-Mn based systems contain several complex metallic alloy phases which recently attract increasing interest. Among them is the orthorhombic Taylor (T) phase, the structure of which is built of atomic layers stacked along the [0 1 0] direction. Along this axis pentagonal columnar clusters are formed.1 The unit cell of the T phase contains 156 atoms with many of the sites with either fractional occupation or mixed Al/Mn occupa-tion, so that a considerable inherent chemical disorder exists on the lattice. As a part of the systematic investi-gation of the transport and magnetic properties of T-Al,Mn based alloys and related quasicrystals, here we present the results of the Hall-effect measurement on T-Al73Mn27 and its solid solutions T-Al73Mn27–xPdx (x = 2, 4 and 6) alloys, and on the triclinic Al73Mn27 phase. EXPERIMENTAL Polycrystalline samples were produced from the consti-tuent elements by levitation induction melting in  a water-cooled copper crucible under argon atmosphere. Annealing at 900 ºC for 312 h and subsequent quen-ching into water yields triclinic Al73Mn27 and  T-Al73Mn27–xPdx (x = 2, 4 and 6) solid solutions. Pure binary T-Al73Mn27 phase was prepared by: annealing at 900 ºC for 312 h, additional annealing at 930 ºC for 3 h, and quenching into water.2 The Hall-effect measure-ments were performed by a standard AC technique and by a five-point method in magnetic fields, B, up to 1 T in the temperature interval from 90 to 370 K. The tem-perature-dependent magnetic susceptibility, χ, was in-vestigated in the temperature interval between 2 and  300 K, using a Quantum Design SQUID magnetometer, equipped with a 5 T magnet. Electrical resistivity was measured between 1.5 and 300 K using the standard four-probe DC technique. RESULTS AND DISCUSSION In the temperature interval explored and for the magnetic 12 J. Ivkov et al., Hall Effect in Al73Mn27 and T-Al73Mn27–xPdx Croat. Chem. Acta 83 (2010) 11. fields up to 1 T the Hall resistivity, ρH, of all the sam-ples is a linear function of the magnetic field and there-fore we present the results for the Hall coefficient, RH = ρH/B, only. The Hall coefficients of the triclinic Al73Mn27 and T-Al73Mn27–xPdx samples as a function of temperature are displayed in Figure 1. The shape of RH vs. T curves indicates that the samples are paramagnetic, and that the anomalous magnetic contribution to the Hall effect is dominant. Generally, in magnetic materials the Hall resisti-vity follows the empirical relation3   ρH = R0 B + μ0M RS, (1)  where R0 and RS are the ordinary and anomalous (spon-taneous) Hall coefficients respectively and M is the magnetization. The normal and anomalous contributions have different origins. The normal Hall effect comes from the Lorentz force acting on the electrons that con-duct electrical current. The anomalous Hall effect, on the other hand, is a consequence of asymmetric scatter-ing which stems from spin-orbit interactions,3 or is due to the influence of the spin-orbit interaction on the elec-tronic wave functions.4  In Figure 2 we present the zero-field-cooled mag-netic susceptibility of the T-Al73Mn27–xPdx and triclinic Al73Mn27 samples as a function of temperature. The mag-netic properties of the T-Al73Mn27–xPdx alloys have been investigated in more detail.5 They belong to the class of magnetically frustrated spin systems with freezing tem-  peratures well below those over which the results were used in this work for the separation of R0 and RS. The high-temperature susceptibility of all alloys follows the Curie-Weiss (χ = χ0 + A/(T – θ)) law with negative Curie-Weiss temperature θ, and temperature independent χ0 < 1×10–5 which we neglect in the fur-ther discussion. As χ is small and (for T > 90 K) of the order 10–3 we ignore the effects of demagnetizing fields and replace μ0M with χ B. Equation (1) then yields  RH = R0 + χ RS . (2) Before we present RH as a function of   we briefly discuss the temperature dependence of R0 and RS. The temperature dependence of R0 is expected to be negligible, as in materials with metallic conductivity. For the anomalous Hall coefficient, it is generally ac-cepted6 that in systems with a high resistivity, ρ, RS is dominated by the side-jump mechanism i.e. by the la-teral displacement which electrons undergo during the scattering in the presence of spin-orbit interaction.7 In this case RS is proportional to ρ2. The electrical resisti-vity of the triclinic Al73Mn27 and T-Al73Mn27–xPdx alloys is shown in Figure 3 as a function of temperature. The values of ρ are rather high and its temperature depen-dence is not negligible, especially in the triclinic Al73Mn27 alloy. Figure 2. Zero-field-cooled magnetic susceptibility ofT-Al73Mn27–xPdx and triclinic Al73Mn27 as a function of tem-perature. T / K0 50 100 150 200 250 300103  02468101214T-Al73Mn27T-Al73Mn21Pd6T / K0 50 100 150 200 250 0.00.51.0 triclinic Al73Mn27T-Al73Mn25Pd2T-Al73Mn23Pd4Figure 1. The Hall coefficient of triclinic Al73Mn27 andT-Al73Mn27–xPdx as a function of temperature. T / K100 150 200 250 300 350 4001010 RH / m3 C-101002003004005001010 RH / m3 C-10510triclinic Al73Mn27T-Al73Mn27T-Al73Mn23Pd4T-Al73Mn21Pd6T-Al73Mn25Pd2Figure 3. The electrical resistivity of triclinic Al73Mn27 andT-Al73Mn27–xPdx as a function of temperature. T / K0 50 100 150 200 250 300103   / cm050100150103   /  cm02468T-Al73Mn27triclinic Al73Mn27T-Al73Mn21Pd6T-Al73Mn25Pd2T-Al73Mn23Pd41010 RH/m3 C–1 1010 RH/m3 C–1 10–3 10–3 J. Ivkov et al., Hall Effect in Al73Mn27 and T-Al73Mn27–xPdx 13 Croat. Chem. Acta 83 (2010) 11. In Figure 4 we plotted RH vs. χ and RH vs. χ ρ2  (arbitrarily normalized to the room temperature values ρr.t.) for the triclinic Al73Mn27, while in Figure 5  we plotted the same for two T-Al73Mn27–xPdx alloys.  We see that RH(T) is a linear function of χ(T ) ρ2(T) and this enables the separation of the coefficients R0 and RS (295 K) as the intercepts and the slopes of the straight lines.3 Because of the small temperature dependence of ρ in the T-Al73Mn27–xPdx alloys, the RH vs. χ plots for these alloys seem (within the experimental error) linear too. A similar dependence of RH(T ) on χ and χ ρ2 was already found in the T-Al73Mn27–xFex (x ≤ 6) alloys.8 The results deduced for R0 and RS are summarized in Table 1. We recall that the number of electrons in  a single band that yields R0 = –1 × 10–10 m3 C–1 is equal to 0.6 × 1023 cm–3 and is characteristic for metals. The absolute values of R0 lower than 1 × 10–10 m3 C–1 do not imply a higher carrier concentration but the mutual cancellation of the contributions from the electron-like and hole-like regions of the Fermi surface.  The anomalous Hall coefficient of all the samples  is rather large which is due to their high resistivity. The values of RS of the T-Al73Mn27–xPdx samples are close to those determined for the T-Al80Mn20 and T-Al78Mn22 phas-es (3.2 and 4.8 × 10–7 m3 C–1 respectively).9 Recently, for the quasicrystalline icosahedral Al70.4Pd20.8Mn8.8 a high  value of RS = 1.8 × 10–5 m3 C–1, close to those obtained for the triclinic Al73Mn27 alloy, has been reported.10  CONCLUSION Hall coefficient RH(T ) of the triclinic Al73Mn27 and Taylor (T) Al73Mn27–xPdx (0 ≤ x ≤ 6) complex metallic alloys is a linear function of χ(T ) ρ2(T ). This enables the separation of the normal and anomalous Hall coeffi-cients R0 and RS respectively, and at the same time con-firms the proposition that in these materials the Hall effect is dominated by the spin-orbit interaction and by the side-jump effect. The anomalous Hall coefficient of all the investigated alloys is very large, due to the high resistivity of these alloys. In the T-Al73Mn27–xPdx sam-ples, RS is of the order 10–7 m3 C–1 and in the triclinic Al73Mn27 sample it is of the order 10–5 m3 C–1. The con-duction electron densities estimated from R0 are charac-teristic for metals and are of the order 1023 cm–3 in the T-Al73Mn27–xPdx samples, and of the order 1022 in the triclinic Al73Mn27 sample. Acknowledgements. This work was done within the activities of the 6th Framework EU Network of Excellence "Complex Metallic Alloys" (Contract No. NMP3-CT-2005-500140), and has been supported in part by the Ministry of Science, Educa-tion and Sports of the Republic of Croatia through the Re-search Project No. 035-0352826-2848. We thank A. Smontara for the fruitfull discussion.  Figure 4. The Hall coefficient of triclinic Al73Mn27 as a func-tion of paramagnetic susceptibility χ, and as a function ofχ ·(ρ /ρr.t.)2. 103 0.0 0.2 0.4 0.61010 RH / m3 C-10100200300400103 .(/r.t.)20 1 2 3triclinic Al73Mn27Figure 5. The Hall coefficient of of T-Al73Mn27–xPdx as afunction of paramagnetic susceptibility χ, and as a function ofχ (ρ/ρr.t.)2. 103 .(/r.t.)20 1 2 3 4 51010 RH / m3 C-10510151030 1 2 3 4 5T-Al73Mn23Pd4T-Al73Mn27T-Al73Mn23Pd4T-Al73Mn27Table 1. The normal Hall coefficient R0 and the anomalous Hall coefficient RS (295 K) deduced from RH vs. χ, and RH vs. χ·(ρ /ρr.t.)2 plots Alloy composition 1010 R0 / m3 C–1 107 RS / m3 C–1 from χ from χρ2  from χ from χρ2 Al73Mn27  – –14 – 160  T-Al73Mn27 –1.6 0.3 4.8 2.7  T-Al73Mn25Pd2 –2.1 –0.6 5.4 3.9  T-Al73Mn23Pd4 –2.1 –0.5 5.0 3.4  T-Al73Mn21Pd6 –1.7 –0.3 5.6 3.7 1010 RH/m3 C–1 1010 RH/m3 C–1 14 J. Ivkov et al., Hall Effect in Al73Mn27 and T-Al73Mn27–xPdx Croat. Chem. Acta 83 (2010) 11. REFERENCES 1. H. Klein, M. Boudard, M. Audier, M. de Boissieu, H. Vincent, L. Beraha, and M. Duneau, Philos. Mag. Lett. 75 (1997) 197–208. 2. S. Balanetskyy, G. Meisterernst, M. Heggen, and M. Feuer-bacher, Intermetallics 16 (2008) 71–87. 3. C. M. Hurd, The Hall Effect in Metals and Alloys, Plenum, New York, 1972. 4. N. A. Sinitsyn, J. Phys.: Condens. Matter 20 (2008) 023201 1–17. 5. J. Dolinšek, J. Slanovec, Z. Jagličić, M. Heggen, S. Balanetskyy,M. Feuerbacher, and K. Urban, Phys. Rev. B 77 (2008) 064430 1–18. 6. T. R. McGuire, R. J. Gambino, and R. C. O’Handley, in: C. L. Chien and C. R. Westgate (Eds.), The Hall Effect and Its Applications, Plenum, New York, 1980, pp. 137–200. 7. L. Berger, Phys. Rev. B 2 (1970) 11, 4559–4566. 8. D. Stanić, J. Ivkov, A. Smontara, Z. Jagličić, J. Dolinšek, M. Heggen, and M. Feuerbacher, Z. Kristallogr. 224 (2009) 49–52. 9. A. Gozlan, C. Berger, G. Fourcaudot, R. Omari., J. C. Lasjaunias, and J. J. Préjean, Phys. Rev. B 44 (1991) 2, 575–583. 10. A. Poddar, S. Das, D. Plachke, and H. D. Carstanjen, J. Magn. Magn. Mater. 300 (2006) 263-272.   SAŽETAK  Hallov efekt u triklinskim Al73Mn27 i T-Al73Mn27–xPdx (0 ≤ x ≤ 6) kompleksnim metalnim slitinama Jovica Ivkov,a Denis Stanić,a Zvonko Jagličić,b Janez Dolinšek,c Marc Heggend i Michael Feuerbacherd aLaboratorij za fiziku transportnih svojstava, Institut za fiziku, Bijenička c. 46,  P. P 304, HR-10001 Zagreb, Hrvatska bInstitute of Mathematics, Physics and Mechanics & Faculty of Civil and Geodetic Engineering, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia cJožef Stefan Institute, University of Ljubljana, Jamova 39, SI-1000 Ljubljana, Slovenia  dInstitut für Festkörperforschung, Forschungszentrum Jülich, Jülich D-52425, Germany Prikazani su rezultati mjerenja Hallovog koeficijenta, RH, triklinske Al73Mn27 slitine i Taylorovih (T) Al73- Mn27–xPdx (x = 0, 2, 4 i 6) faza kompleksnih metalnih slitina u intervalu temperatura od 90 do 400 K. Hallov koefi-cijent svih slitina je pozitivan i brzo opada s porastom temperature T. Za odijeljivanje normalnog, R0, i anomalnog, RS, Hallovog koeficijenta korišteni su rezultati za paramagnetsku susceptibilnost, χ(T ), i električnu otpornost, ρ(T ). Dobro definirana linearna ovisnost RH o χ(T ) ρ2(T ) potvrđuje pretpostavku da je u tim materijalima RH pretežito određen spin-orbit interakcijom. Vrijednosti određene iz RH vs. χ i RH vs. χρ2 prikaza za T-AlMnPd  slitine, padaju između –2×10–10 m3 C–1   i 0 za R0, a iznose oko 5×10–7 m3 C–1 za RS. Vrijednosti određene  iz RH vs. χρ2 prikaza za triklinsku Al73Mn27 slitinu iznose oko –15×10–10 m3 C–1 za R0, i oko 1.5×10–5 m3 C–1 za RS.  

Hall Effect of the Triclinic Al73Mn27 and T-Al73Mn27–xPdx (0 ≤ x ≤ 6) Complex Metallic Alloys

The Hall coefficient, R-H, of the triclinic Al73Mn27 and Taylor-phase Al73Mn27-xPdx (x = 0, 2, 4 and 6) complex metallic alloys has been measured from 90 to 400 K. The Hall coefficients of all the samples are positive and they decrease strongly with the increase of temperature, T. For the separation of the normal, R-0, and anomalous, R-S, Hall coefficient the results for the paramagnetic susceptibility, chi(T), and electrical resistivity, rho(T), have been used. The well defined linearity of the R-H vs. chi(T) . rho(2)(T) plots confirms the assumption that in these materials R-H is dominated by spin-orbit interaction. The values deduced from the R-H vs. chi and R-H vs. chi.rho(2) plots in T-AlMnPd phases, fall between -2 x 10(-10) m(3) C-1 and 0 for R-0, and are about 5 x 10(-7) m(3) C-1 for R-S. The values deduced from the R-H vs. chi.rho(2) plots in the triclinic Al73Mn27 alloy are about -15 x 10(-10) m(3) C-1 for R-0, and about 1.5 x 10(-5) m(3) C-1 for R-S

Ivkov, J.

Stanic, D.

Jaglicic, Z.

Dolinsek, J.

Heggen, M.

Feuerbacher, M.

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Hall Effect of the Triclinic Al73Mn27 and T-Al73Mn27-xPdx (0x6) Complex Metallic Alloys

Hall Effect of the Triclinic Al73Mn27 and T-Al73Mn27–xPdx (0 ≤ x ≤ 6) Complex Metallic Alloys

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