Magnetoresistance and thermopower of crossed NiCr and CoCr nanowire networks have been measured as a function of temperature and chromium content in dilute alloys. At low temperatures, it is found that the impurity effect leads to negative anisotropic magnetoresistance, an observation that even persists until room temperature in diluted CoCr alloy nanowires. The addition of a small amount of Cr in nickel nanowires also abruptly reverses the sign of the thermopower from −20 μV/K for pure Ni up to +18 μV/K for the dilute alloys, implying the switching from n- to p-type conduction. These results are consistent with pronounced changes in the density of states for the majority spin electrons. The high room-temperature power factors of these magnetic nanowire networks (in the range of 1–10 mW/K2 m) provide interesting perspectives for designing n- and p-type legs for flexible spin thermoelectric devices.
References
1.
I.
Campbell
and A.
Fert
, “Chapter 9 Transport properties of ferromagnets
,” Handbook of Ferromagnetic Materials
(Elsevier
, 1982
), Vol. 3
.2.
J.-I.
Inoue
, “Chapter 2—gmr, tmr and bmr
,” in Nanomagnetism and Spintronics
, edited by T.
Shinjo
(Elsevier
, Amsterdam
, 2009
), pp. 15
–92
.3.
H. C.
Van Elst
, “The anisotropy in the magneto-resistance of some nickel alloys
,” Physica
25
, 708
–720
(1959
).4.
I. A.
Campbell
, A.
Fert
, and O.
Jaoul
, “The spontaneous resistivity anisotropy in ni-based alloys
,” J. Phys. C: Solid State Phys.
3
, S95
(1970
).5.
J. W. F.
Dorleijn
and A. R.
Miedema
, “An investigation of the resistivity anisotropy in nickel alloys
,” J. Phys. F: Met. Phys.
5
, 1543
–1553
(1975
).6.
F. J.
Blatt
, P. A.
Schroeder
, C. L.
Foiles
, and D.
Greig
, Thermoelectric Power of Metals
(Springer
, Boston, MA
, 1976
).7.
T.
Farrell
and D.
Greig
, “The thermoelectric power of nickel and its alloys
,” J. Phys. C: Solid State Phys.
3
, 138
(1970
).8.
M. C.
Cadeville
and J.
Roussel
, “Thermoelectric power and electronic structure of dilute alloys of nickel and cobalt with d transition elements
,” J. Phys. F: Met. Phys.
1
, 686
(1971
).9.
M.
Hatami
, G. E. W.
Bauer
, Q.
Zhang
, and P. J.
Kelly
, “Thermal spin-transfer torque in magnetoelectronic devices
,” Phys. Rev. Lett.
99
, 066603
(2007
).10.
K.
Uchida
, J.
Xiao
, H.
Adachi
, J.
Ohe
, S.
Takahashi
, J.
Ieda
, T.
Ota
, Y.
Kajiwara
, H.
Umezawa
, H.
Kawai
et al., “Spin seebeck insulator
,” Nat. Mater.
9
, 894
(2010
).11.
G. E. W.
Bauer
, E.
Saitoh
, and B. J.
van Wees
, “Spin caloritronics
,” Nat. Mater.
11
, 391
(2012
).12.
A.
Pushp
, T.
Phung
, C.
Rettner
, B. P.
Hughes
, S.-H.
Yang
, and S. S. P.
Parkin
, “Giant thermal spin-torque–assisted magnetic tunnel junction switching
,” Proc. Natl. Acad. Sci.
112
, 6585
–6590
(2015
).13.
S. R.
Boona
, R. C.
Myers
, and J. P.
Heremans
, “Spin caloritronics
,” Energy Environ. Sci.
7
, 885
–910
(2014
).14.
K.
Vandaele
, S. J.
Watzman
, B.
Flebus
, A.
Prakash
, Y.
Zheng
, S. R.
Boona
, and J. P.
Heremans
, “Thermal spin transport and energy conversion
,” Mater. Today Phys.
1
, 39
–49
(2017
).15.
J.
He
and T. M.
Tritt
, “Advances in thermoelectric materials research: Looking back and moving forward
,” Science
357
, eaak9997
(2017
).16.
J.-H.
Bahk
, H.
Fang
, K.
Yazawa
, and A.
Shakouri
, “Flexible thermoelectric materials and device optimization for wearable energy harvesting
,” J. Mater. Chem. C
3
, 10362
–10374
(2015
).17.
Q.
Zhang
, Y.
Sun
, W.
Xu
, and D.
Zhu
, “Organic thermoelectric materials: Emerging green energy materials converting heat to electricity directly and efficiently
,” Adv. Mater.
26
, 6829
–6851
(2014
).18.
Y.
Du
, J.
Xu
, B.
Paul
, and P.
Eklund
, “Flexible thermoelectric materials and devices
,” Appl. Mater. Today
12
, 366
–388
(2018
).19.
T.
da Câmara Santa Clara Gomes
, F.
Abreu Araujo
, and L.
Piraux
, “Making flexible spin caloritronic devices with interconnected nanowire networks
,” Sci. Adv.
5
, eaav2782
(2019
).20.
F.
Abreu Araujo
, T.
da Câmara Santa Clara Gomes
, and L.
Piraux
, “Magnetic control of flexible thermoelectric devices based on macroscopic 3d interconnected nanowire networks
,” Adv. Electron. Mater.
5
, 1800819
(2019
).21.
A.
Fert
and L.
Piraux
, “Magnetic nanowires
,” J. Magn. Magn. Mater.
200
, 338
–358
(1999
).22.
M.
Staňo
, O.
Fruchart
, and E.
Brück
, “Chapter 3—Magnetic nanowires and nanotubes
,” Handbook of Magnetic Materials
(Elsevier
, 2018
), Vol. 27
, pp. 155
–267
.23.
T.
Böhnert
, V.
Vega
, A.-K.
Michel
, V. M.
Prida
, and K.
Nielsch
, “Magneto-thermopower and magnetoresistance of single co-ni alloy nanowires
,” Appl. Phys. Lett.
103
, 092407
(2013
).24.
O.
Yamashita
, S.
Tomiyoshi
, and K.
Makita
, “Bismuth telluride compounds with high thermoelectric figures of merit
,” J. Appl. Phys.
93
, 368
–374
(2002
).25.
M.
Rauber
, I.
Alber
, S.
Müller
, R.
Neumann
, O.
Picht
, C.
Roth
, A.
Schökel
, M. E.
Toimil-Molares
, and W.
Ensinger
, “Highly-ordered supportless three-dimensional nanowire networks with tunable complexity and interwire connectivity for device integration
,” Nano Lett.
11
, 2304
–2310
(2011
).26.
E.
Araujo
, A.
Encinas
, Y. G.
Velázquez-Galván
, J. M.
Martínez-Huerta
, G.
Harmoir
, E.
Ferain
, and L.
Piraux
, “Artificially modified magnetic anisotropy in interconnected nanowire networks
,” Nanoscale
7
, 1485
–1490
(2015
).27.
E.
Ferain
and R.
Legras
, “Track-etch templates designed for micro- and nanofabrication
,” Nucl. Instrum. Methods Phys. Res., Sect. B
208
, 115
–122
(2003
).28.
T.
da Câmara Santa Clara Gomes
, J.
De La Torre Medina
, Y. G.
Velázquez-Galván
, J. M.
Martínez-Huerta
, A.
Encinas
, and L.
Piraux
, “Interplay between the magnetic and magneto-transport properties of 3d interconnected nanowire networks
,” J. Appl. Phys.
120
, 043904
(2016
).29.
T.
McGuire
, J.
Aboaf
, and E.
Klokholm
, “Negative anisotropic magnetoresistance in 3d metals and alloys containing iridium
,” IEEE Trans. Magn.
20
, 972
–974
(1984
).30.
O.
Jaoul
, I.
Campbell
, and A.
Fert
, “Spontaneous resistivity anisotropy in ni alloys
,” J. Magn. Magn. Mater.
5
, 23
–34
(1977
).31.
J.
Durand
and F.
Gautier
, “Conduction a deux bandes et effet de periode dans les alliages a base de nickel et de cobalt
,” J. Phys. Chem. Solids
31
, 2773
–2787
(1970
).32.
Y. D.
Yao
, S.
Arajs
, and E. E.
Anderson
, “Electrical resistivity of nickel-rich nickel-chromium alloys between 4 and 300 k
,” J. Low Temp. Phys.
21
, 369
–376
(1975
).33.
S. R.
Boona
and D. T.
Morelli
, “Enhanced thermoelectric properties of cepd3−xptx
,” Appl. Phys. Lett.
101
, 101909
(2012
).© 2019 Author(s).
2019
Author(s)
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