The longitudinal spin Seebeck effect (LSSE) has been investigated in high-quality epitaxial CoFe2O4 (CFO) thin films. The thermally excited spin currents in the CFO films are electrically detected in adjacent Pt layers due to the inverse spin Hall effect. The LSSE signal exhibits a linear increase with increasing temperature gradient, yielding a LSSE coefficient of ∼100 nV/K at room temperature. The temperature dependence of the LSSE is investigated from room temperature down to 30 K, showing a significant reduction at low temperatures, revealing that the total amount of thermally generated magnons decreases. Furthermore, we demonstrate that the spin Seebeck effect is an effective tool to study the magnetic anisotropy induced by epitaxial strain, especially in ultrathin films with low magnetic moments.

1.
K.
Uchida
,
S.
Takahashi
,
K.
Harii
,
J.
Ieda
,
W.
Koshibae
,
K.
Ando
,
S.
Maekawa
, and
E.
Saitoh
,
Nature
455
,
778
(
2008
).
2.
C. M.
Jaworski
,
J.
Yang
,
S.
Mack
,
D. D.
Awschalom
,
J. P.
Heremans
, and
R. C.
Myers
,
Nat. Mater.
9
,
898
(
2010
).
3.
S.
Bosu
,
Y.
Sakuraba
,
K.
Uchida
,
K.
Saito
,
T.
Ota
,
E.
Saitoh
, and
K.
Takanashi
,
Phys. Rev. B
83
,
224401
(
2011
).
4.
K.
Uchida
,
J.
Xiao
,
H.
Adachi
,
J.
Ohe
,
S.
Takahashi
,
J.
Ieda
,
T.
Ota
,
Y.
Kajiwara
,
H.
Umezawa
,
H.
Kawai
,
G. E. W.
Bauer
,
S.
Maekawa
, and
E.
Saitoh
,
Nat. Mater.
9
,
894
(
2010
).
5.
W.
Jiang
,
P.
Upadhyaya
,
Y.
Fan
,
J.
Zhao
,
M.
Wang
,
L.
Chang
,
M.
Lang
,
K. L.
Wong
,
M.
Lewis
,
Y.
Lin
,
J.
Tang
,
S.
Cherepov
,
X.
Zhou
,
Y.
Tserkovnyak
,
R. N.
Schwartz
, and
K. L.
Wang
,
Phys. Rev. Lett.
110
,
177202
(
2013
).
6.
G. E. W.
Bauer
,
E.
Saitoh
, and
B. J.
van Wees
,
Nat. Mater.
11
,
391
399
(
2012
).
7.
S. R.
Boona
,
R. C.
Myers
, and
J. P.
Heremans
,
Energy Environ. Sci.
7
,
885
910
(
2014
).
8.
K.
Uchida
,
T.
Nonaka
,
T.
Kikkawa
,
Y.
Kajiwara
, and
E.
Saitoh
,
Phys. Rev. B
87
,
104412
(
2013
).
9.
Y.
Ohnuma
,
H.
Adachi
,
E.
Saitoh
, and
S.
Maekawa
,
Phys. Rev. B
87
,
014423
(
2013
).
10.
J.
Xiao
,
G. E. W.
Bauer
,
K. C.
Uchida
,
E.
Saitoh
, and
S.
Maekawa
,
Phys. Rev. B
81
,
214418
(
2010
).
11.
H.
Adachi
,
K.
Uchida
,
E.
Saitoh
,
J.
Ohe
,
S.
Takahashi
, and
S.
Maekawa
,
Appl. Phys. Lett.
97
,
252506
(
2010
).
12.
M.
Schreier
,
N.
Roschewsky
,
E.
Dobler
,
S.
Meyer
,
H.
Huebl
,
R.
Gross
, and
S. T. B.
Goennenwein
,
Appl. Phys. Lett.
103
,
242404
(
2013
).
13.
S.
Geprägs
,
A.
Kehlberger
,
E. J.
Guo
,
T.
Schulz
,
C.
Mix
,
F.
Della Coletta
,
S.
Meyer
,
A.
Kamra
,
M.
Althammer
,
G.
Jakob
,
H.
Huebl
,
R.
Gross
,
S. T. B.
Goennenwein
, and
M.
Kläui
, “
Spin Seebeck effect: a powerful probe of magnon properties in compensated ferrimagnets
,” Nature Communications (to be published); e-print arXiv:1405.4971.
14.
D.
Meier
,
T.
Kuschel
,
L.
Shen
,
A.
Gupta
,
T.
Kikkawa
,
K.
Uchida
,
E.
Saitoh
,
J.-M.
Schmalhorst
, and
G.
Reiss
,
Phys. Rev. B
87
,
054421
(
2013
).
15.
K.
Uchida
,
T.
Nonaka
,
T.
Ota
, and
E.
Saitoh
,
Appl. Phys. Lett.
97
,
262504
(
2010
).
16.
S. F.
Rus
,
A.
Herklotz
,
R.
Roth
,
L.
Schultz
, and
K.
Dörr
,
J. Appl. Phys.
114
,
043913
(
2013
).
17.
D.
Fritsch
and
C.
Ederer
,
Phys. Rev. B
86
,
014406
(
2012
).
18.
J. H.
Park
,
J.-H.
Lee
,
M. G.
Kim
,
Y. K.
Jeong
,
M. A.
Oak
,
H. M.
Jang
,
H. J.
Choi
, and
J. F.
Scott
,
Phys. Rev. B
81
,
134401
(
2010
).
19.
M.
Isasa
,
A.
Bedoya-Pinto
,
S.
Velez
,
F.
Golmar
,
F.
Sanchez
,
L. E.
Hueso
,
J.
Fontcuberta
, and
F.
Casanova
,
Appl. Phys. Lett.
105
,
142402
(
2014
).
20.
Z.
Wang
,
R.
Viswan
,
B.
Hu
,
J.-F.
Li
,
V. G.
Harris
, and
D.
Viehland
,
J. Appl. Phys.
111
,
034108
(
2012
).
21.
A.
Kehlberger
,
U.
Ritzmann
,
D.
Hinzke
,
E. J.
Guo
,
J.
Cramer
,
G.
Jakob
,
M. C.
Onbasli
,
D. H.
Kim
,
C. A.
Ross
,
M. B.
Jungfleisch
,
B.
Hillebrands
,
U.
Nowak
, and
M.
Kläui
, “
Length scale of spin Seebeck effect
,”
Phys. Rev. Lett.
115
,
096602
(
2015
).
22.
U.
Ritzmann
,
D.
Hinzke
,
A.
Kehlberger
,
E. J.
Guo
,
M.
Kläui
, and
U.
Nowak
,
Phys. Rev. B
92
,
174411
(
2015
).
23.
E. J.
Guo
,
A.
Kehlberger
,
J.
Cramer
,
G.
Jakob
, and
M.
Kläui
, “
Influence of thickness and interface on the low-temperature enhancement of spin Seebeck effect in YIG thin films
,” e-print arXiv:1506.06037.
24.
H.
Jin
,
S. R.
Boona
,
Z.
Yang
,
R. C.
Myers
, and
J. P.
Heremans
, “
The effect of the magnon dispersion on the longitudinal spin Seebeck effect in yttrium iron garnets (YIG)
,”
Phys. Rev. B
92
,
054436
(
2015
).
25.
T.
Kikkawa
,
K.
Uchida
,
S.
Daimon
,
Z.
Qiu
,
Y.
Shiomi
, and
E.
Saitoh
,
Phys. Rev. B
92
,
064413
(
2015
).
26.
S. R.
Boona
and
J. P.
Heremans
,
Phys. Rev. B
90
,
064421
(
2014
).
27.
R.
Bhattacharya
, “
Chemical bath deposition, electrodeposition, and electro less deposition of semiconductors, superconductors, and oxide materials
,” in
Solution Processing of Inorganic Materials
, edited by
D. B.
Mitzi
(
John Wiley & Sons, Inc.
,
Hoboken, NJ, USA
,
2008
), Chap. 7.
28.
See supplemental material at http://dx.doi.org/10.1063/1.4939625 for more details on the comparison of the spin Seebeck voltages and the magnetization as a function of magnetic field for two CFO films at room temperature.
29.
A.
Aqeel
,
N.
Vlietstra
,
J. A.
Heuver
,
G. E. W.
Bauer
,
B.
Noheda
,
B. J.
van Wees
, and
T. T. M.
Palstra
,
Phys. Rev. B
92
,
224410
(
2015
).
30.
T.
Niizeki
,
T.
Kikkawa
,
K.
Uchida
,
M.
Oka
,
K. Z.
Suzuki
,
H.
Yanagihara
,
E.
Kita
, and
E.
Saitoh
,
AIP Advances
5
,
053603
(
2015
).

Supplementary Material

You do not currently have access to this content.