我們報導了有趣的雙鈣鈦礦系統Pr2CoMnO6(PCMO)，其具有巨大
介電常數和磁介電效應。從阿瑞尼士作圖(Arrhenius plot)所得到的活化
能(activation energy) Ea = 0.18 eV以及變溫介電常數所顯示的熱活化行
為(thermally activated behavior)指出高介電常數來源並非由鐵電相變所
造成，而是從內部的介面電容所造成。另一方面，外加磁場9 Tesla，
在 Tm ~ 150 K(頻率為10 kHz)磁介電效應相較於無外加磁場可達
20%。且由阻抗分析可以得到晶粒電阻(Rg)在外加磁場下有負磁阻變
化(~ -20% 在150 K)，而所觀察到的正磁介電效應其來源與負磁阻變
化相關。同時在150 K附近也有著顯著的鐵磁性，相變溫度與磁介電效
應、磁阻效應的150 K相近。上述這些實驗顯示鐵磁性相變會引發磁阻
與磁介電效應。

We report an intriguing giant dielectric and magnetodielectric (MD)
response on double perovskite Pr2CoMnO6(PCMO) system. The Arrhenius
plot indicates that the origin of giant dielectric is internal barrier layer
capacitance. Meanwhile, at the highest applied magnetic field 9T, the giant
dielectric constant around Tm ~ 150 K is enhanced almost ~ 20% (at 10 kHz
frequency) compared with that at zero field. The observed positive MD
effect is considered to be associated with the direct consequence of
negative magnetoresistance changes (~ -20% at 150 K) which was
calculated by temperature dependent impedance spectras. Concomitantly, a
pronounced ferromagnetic ordering is observed near Tc ~ 150 K coinciding
with Tm of ε′(T). These experimental results suggest that the
magnetoresistive and MD effect response is very strongly by magnetic
property of PCMO.

致謝............................................................................................................... I
論文摘要......................................................................................................II
ABSTRACT .............................................................................................. III
目錄.............................................................................................................IV
圖目錄..........................................................................................................V
第 一 章 簡介.............................................................................................1
1-1 前言.................................................................................................... 1
1-2 研究動機............................................................................................ 7
第 二 章 實驗介紹.....................................................................................8
2-1 樣品製備............................................................................................ 8
2-2 磁性量測儀器.................................................................................... 9
2-3 電性量測儀器.................................................................................. 12
第 三 章 磁性與電性探討......................................................................15
3-1 磁性種類........................................................................................... 15
3-2 磁性實驗結果.................................................................................. 18
3-3 阻抗頻譜介紹.................................................................................. 22
3-4 介電性質........................................................................................... 25
3-5 磁介電效應...................................................................................... 32
第 四 章 結果與討論...............................................................................38
參考文獻.....................................................................................................41

[1] K. D. Truong, J. Laverdiere, M. P. Singh, S. Jandl, and P. Fournier,
'Impact of Co/Mn cation ordering on phonon anomalies in La2CoMnO6
double perovskites:Raman spectroscopy', Phys. Rev. B 76, 132413
(2007)
[2] H. Z. Guo, A. Gupta, Jiandi. Zhang, M. Varela, and S. J. Pennycook,
'Effect of oxygen concentration on the magnetic properties of
La2CoMnO6 thin films', Appl. Phys. Lett. 91, 202509 (2007)
[3] N. S. Ragodo, J. Li, A. W. Sleight, and M. A. Subrammanian,
'Magnetocapacitance and magnetoresistance near room temperature in a
ferromagnetic semiconductor: La2NiMnO6', Adv. Mater. 17, 2225 (2005)
[4] J. B. Goodenough, 'Theory of the role of covalence in the perovskite-type
manganites [La, M(II)]MnO3', Phys. Rev. 100, 564 (1955)
[5] J. Kanamori, 'Superexchange interaction and symmetry properties of
electron orbitals', J. Phys. Chem. Solids 10, 87 (1959)
[6] H. Z. Guo, A. Gupta, T. G. Calvarese, and M. A. Subramanian,
'Structural and magnetic properties of epitaxial thin films of the ordered
double perovskite La2CoMnO6', Appl. Phys. Lett. 89, 262503 (2006)
[7] M. P. Singh, K. D. Truong, and P. Fournier, 'Magnetodielectric effect in
double perovskite La2CoMnO6 thin films', Appl. Phys. Lett. 91, 042504
(2007)
[8] R. I. Dass, and J. B. Goodenough, 'Multiple magnetic phases of
La2CoMnO6-δ(0≤δ≤0.5) ', Phys. Rev. B 67, 014401 (2003)
[9] M. P. Singh, K. D. Truong, S. Jandl, and P. Fournier, 'Magnetic
properties and phonon behavior of Pr2NiMnO6 thin films', Appl. Phys.
Lett. 98, 162506 (2011)
[10] D. Choudhury, P. Mandal, R. Mathieu, A. Hazarika, S. Rajan, A.
Sundaresan, U.V. Waghmare, R. Knut, O. Karis, P. Nordblad, and D. D.
Sarma1, 'Near-room-temperature colossal magnetodielectricity and
multiglass properties in partially disordered La2NiMnO6', Phys. Rev.
Lett. 108, 127201 (2011)
[11] W. Eerenstein, N. D. Mathur and J. F. Scott, ' Multiferroic and
magnetoelectric materials' , Nature 442, 759 (2006)
[12] T. Kimura, T. Goto, H. Shintani, K. Ishizaka, T. Arima, and Y. Tokura,
'Magnetic control of ferroelectric polarization', Nature (London) 426,
55 (2003)
[13] S. W. Cheong and M. Mostovoy, 'Multiferroics: a magnetic twist for
ferroelectricity', Nature Mater. 6, 13 (2007)
[14] G. Lawes, A. B. Harris, T. Kimura, N. Rogado, R. J. Cava, A. Aharony,
O. Entin-Wohlman, T. Yildirim, M. Kenzelmann, C. Broholm, and A. P.
Ramirez, 'Magnetically driven ferroelectric order in Ni3V2O8', Phys. Rev.
Lett. 95, 087205 (2005)
[15] L. C. Chapon, G. R. Blake, M. J. Gutmann, S. Park, N. Hur, P. G.
Radaelli, and S. W. Cheong., 'Structural anomalies and multiferroic
behavior in magnetically frustrated TbMn2O5', Phys. Rev. Lett. 93,
177402 (2004)
[16] N. Aliouane, D. N. Argyriou, J. Strempfer, I. Zegkinoglou, S. Landsgesell,
and M. V. Zimmermann, 'Field-induced linear magnetoelastic coupling
in multiferroic TbMnO3', Phys. Rev. B 73, 020102 (2006)
[17] B. B. Van Aken, T. T. M. Palstra, A. Filippetti, and N. A. Spaldin, 'The
origin of ferroelectricity in magnetoelectric YMnO3', Nature Mater. 3,
164 (2004)
[18] N. Hur, S. Park, P. A. Sharma, J. S. Ahn, S. Guha, and S. W. Cheong,
'Electric polarization reversal and memory in a multiferroic material
induced by magnetic fields', Nature 429, 392 (2004)
[19] M. P. Singh, W. Prellier, C. Simon, and B. Raveau, 'Magnetocapacitance
effect in perovskite-superlattice based multiferroics', Appl. Phys. Lett. 87,
22505 (2005)
[20] N. Hur, S. Park, P. A. Sharma, J. S. Ahn, S. Guha, and S. W. Cheong,
'Electric polarization reversal and memory in a multiferroic material
induced by magnetic fields', Nature 429, 392 (2004)
[21] N. A. Hill, 'Why are there so few magnetic ferroelectrics? ', J. Phys.
Chem. B 104, 6694 (2000)
[22] R. Seshadri and N. A. Hill, 'Visualizing the role of Bi 6s “Lone Pairs” in
the off-center distortion in ferromagnetic BiMnO3', Chem. Mater. 13,
2892 (2001)
[23] M. Fiebig, 'The revival of the magneto-electric effect', J. Phys. D 38, 123
(2005)
[24] H. Katsura, N. Nagaosa, and A. V. Balatsky, 'Spin current and
magnetoelectric effect in noncollinear magnets', Phys. Rev. Lett. 95,
057205 (2005)
[25] M. Alexe, M. Ziese, D. Hesse, P. Esquinazi, K. Yamauchi, T. Fukushima,
S. Picozzi, and U. Gosele, 'Ferroelectric switching in multiferroic
magnetite (Fe3O4) thin films', Adv. Mater. 21 4452 (2009)
[26] N. Ikeda, H. Ohsumi, K. Ohwada, K. Ishii, K. Inami, T. Kakurai, Y.
Murakami, K. Yoshii, S. Mori, Y. Horibe, and H. Kito, 'Ferroelectricity
from iron valence ordering in the charge-frustrated system LuFe2O4',
Nature 436 1136 (2005)
[27] M. A. Subramanian, T. He, J. Chen, N. S. Rogado, T. G. Calvarese, and A.
W. Sleight, 'Giant room-temperature magnetodielectric response in the
electronic ferroelectric LuFe2O4', Adv. Mater. 18 1737 (2006)
[28] S. Song and F. Placido, 'The influence of phase probability distributions
on impedance spectroscopy', J. Stat. Mech.: Theor. Exp., 10, P10018
(2004)
[29] T. B. Adams, D. C. Sinclair, and A. R. West, 'Giant barrier layer
capacitance effects in CaCu3Ti4O12 ceramics', Adv. Mater. 14, 1321
(2002)
[30] P. K. Jana, S. Sarkar, and B. K. Chaudhuri, 'Low loss giant dielectric and
electrical transport behavior of KxTiyNi1−x−yO system', Appl. Phys. Lett.
88, 182901 (2006)
[31] P. Lunkenheimer, V. Bobnar, A. V. Pronin, A. I. Ritus, A. A. Volkov, and
A. Loidl1, 'Origin of apparent colossal dielectric constants', Phys. Rev.
B 66, 052105 (2002)
[32] B. G. Kim, S. M. Cho, T. Y. Kim, and H. M. Jang, 'Giant dielectric
permittivity observed in Pb-based perovskite ferroelectrics', Phys. Rev.
Lett. 86, 3404 (2001)
[33] G. Catalan, D. O’Neill, R. M. Bowman, and J. M. Gregg, 'Relaxor
features in ferroelectric superlattices: A Maxwell–Wagner approach',
Appl. Phys. Lett. 77, 3078 (2000)
[34] H. Das, U. V. Waghmare, T. Saha-Dasgupta, and D. D. Sarma,
'Electronic structure, phonons, and dielectric anomaly in ferromagnetic
insulating double pervoskite La2NiMnO6', Phys. Rev. Lett. 100, 186402
(2008)
[35] H. Das, U. V. Waghmare, T. Saha-Dasgupta, and D. D. Sarma,
'Theoretical evidence and chemical origin of the magnetism-dependent
electrostructural coupling in La2NiMnO6', Phys. Rev. B 79, 144403
(2009)
[36] G. Lawes, 'Charge hopping in glassy magnets', Physics 5, 35 (2012)
[37] S. Mukherjee, C. H. Chen, C. C. Chou, K. F. Tseng, B. K. Chaudhuri, and
H. D. Yang, 'Colossal dielectrics and magnetodielectric effect in Er2O3
nanoparticles embedded SiO2 glass matrix',' Phys. Rev. B 82, 104107
(2010)
[38] S. Mukherjee, P. Dasgupta1 and P. K. Jana, 'Size-dependent dielectric
behaviour of magnetic Gd2O3 nanocrystals dispersed in a silica matrix', J.
Phys. D: Appl. Phys. 41, 215004 (2008)
[39] S. Mukherjee, C. H. Chen, C. C. Chou and H. D. Yang, 'Anomalous
dielectric behavior in nanoparticle Eu2O3 : SiO2 glass composite system ',
Eurpphys. Lett. 92, 57010 (2010)
[40] G. Catalan, 'Magnetocapacitance without magnetoelectric coupling',
Appl. Phys. Lett. 88, 102902 (2006)