磁性对BiAlO3/La0.67Sr0.33MnO3异质结构介电与极化性质的影响
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"本文探讨了磁性对BiAlO3 / La0.67Sr0.33MnO3异质结构中介电常数和极化特性的影响。研究通过脉冲激光沉积技术在LaAlO3（111）衬底上制备了这种特殊结构。实验发现，在La0.67Sr0.33MnO3的金属-绝缘体相变温度（TMI）附近的磁场为1T时，存在显著的磁阻效应。同时，该结构的磁电常数在La0.67Sr033MnO3的TMI附近表现出异常，而铁电极化在磁场及变化下有所增加。这些异常现象可能与La0.67Sr0.33MnO3的相变过程有关。与单一的La0.67Sr0.33MnO3层相比，BiAlO3 / La0.67Sr0.33MnO3异质结构的磁矩有明显提升，这可能源于界面处的自旋轨道耦合作用。此外，相对磁化强度的变化同样在La0.67Sr0.33MnO3的TMI附近显示出异常行为。"
在本文中，作者深入研究了磁性如何改变BiAlO3和La0.67Sr0.33MnO3组成的异质结构的介电和极化性质。BiAlO3是一种铁电材料，而La0.67Sr0.33MnO3则具有磁性和电输运特性。通过脉冲激光沉积技术，科学家能够精确控制这些材料的层叠，形成具有复杂相互作用的异质结构。
实验观察到的磁阻效应表明，当磁场强度达到1T时，La0.67Sr0.33MnO3的电阻率发生显著变化，这与材料的金属-绝缘体相变有关。磁电常数的异常则揭示了磁性状态对电介质性能的直接影响，这在多铁性材料研究中尤为重要，因为它们允许通过磁场调控电性质。同时，铁电极化的增强表明磁场不仅影响导电性，还影响材料的极化能力。
BiAlO3 / La0.67Sr0.33MnO3异质结构中的磁矩增加是一个关键发现，这可能由界面处的自旋轨道耦合作用引起。这种耦合使得电子的自旋状态与轨道运动相互关联，从而改变了材料的磁性特性。相对磁化强度的异常进一步证实了La0.67Sr0.33MnO3的TMI附近存在特殊的物理现象，这可能与材料内部的相变和结构重排有关。
人工薄膜异质结构的研究为设计新型多功能材料提供了可能性，特别是在磁电、磁光和磁热等多物理性质的集成方面。这些发现对于开发下一代信息存储和处理设备，如磁电随机存取存储器（MRAM）和其他磁性传感器具有重要意义。通过理解并利用这些复杂的相互作用，科学家可以创建出更高效、更灵活的电子器件，推动信息技术的进步。
Magnetic Effects on the Dielectric and Polarization
Properties in BiAlO
3
/La
0.67
Sr
0.33
MnO
3
Heterostructure
Yanan Zhao, Bingcheng Luo, Changle Chen,* Hui Xing, Jianyuan Wang, and Kexin Jin
BiAlO
3
/La
0.67
Sr
0.33
MnO
3
heterostructure was fabricated on LaAlO
3
(111)
substrate by pulsed laser deposition technology. A remarkable magneto-
resistivity effect was detected at H ¼ 1 T near the metal–insulator phase
transition temperature (T
MI
)ofLa
0.67
Sr
0.33
MnO
3
. The magneto-dielectric
constant shows an anomaly near T
MI
of La
0.67
Sr
0.33
MnO
3
, whereas the
ferroelectric polarization increases under magnetic field and its variation
shows the similar anomaly near T
MI
of La
0.67
Sr
0.33
MnO
3
, which could be
assigned to the important role of the phase transformation of
La
0.67
Sr
0.33
MnO
3
. The magnetic moment of the BiAlO
3
/La
0.67
Sr
0.33
MnO
3
heterostructure distinctly arises compared to the single La
0.67
Sr
0.33
MnO
3
layer, probably on account of the spin–orbit coupling effect at the interface,
and the relative magnetization variation also shows an anomaly near T
MI
of
La
0.67
Sr
0.33
MnO
3
.
Artificial thin film heterostructures composed of ferroelectric
and ferromagnetic materials could also obtain magnetoelec-
tric coupling, like in the case of single-phase materials.
[1,2]
The
well-known BiMO
3
ferroelectric oxides (M ¼ Mn,Fe,Al,and
In), known as lead-free ferroelectrics, have attracted signifi-
cant interest on ac count of the stereochemical active 6s
2
lone
pair on Bi
3þ
.
[3–5]
Especially, bulk BiAlO
3
(BAO) has po lar R3c
symmetry with the large remnant polarization (P
r
)of
75.6 mCcm
2
and high Curie temperature (T
C
)around
820 K.
[6,7]
Therefore, ferroelectric BAO layer could be used
for the composition of heterostructures, resembling the
situationobservedinBiFeO
3
(BFO).
[8]
On the other hand,
La
0.67
Sr
0.33
MnO
3
(LSMO) is a half-metallic material not only
used as a ferromagnetic layer but also as the b ottom electrode
in heterostructures, and it exhibits a colossal negative
magneto-resistance (MR) effect
[9]
with appropriate lattice
parameter (3.87 A
)
[10]
which matches well that of the
perovskite ferroelectric material. Besides, LSMO has a
metal–insulator transition temperature
(T
MI
) near the Curie temperature (T
C
),
but with different depositing and anneal-
ing processes the T
C
may be greater or
less than T
MI
.
[11]
Several experimental researches dem-
onstrated that the P
r
of bulk BAO
polycrystalline was 9.5 or 12 mCcm
2
at
room temperature (RT),
[12,13]
and was
about 29 mCcm
2
in tetragonal phase of
BAO thin films at RT,
[14]
respectively.
Very recently, we analyzed the tempera-
ture dependence of conduction mecha-
nism of BAO thin films.
[15]
Notably,
Silveira et al.
[16]
theoretically indicated
that BAO could exhibit a coexistence of
ferroelectricity and Rashba-type spin
splitting effect. Hence, the BAO-based
oxide heterostructures may initiate many considerable and
fancy interface and surface effects, e.g., for the improved
magnetic moment and the two-dimensional electron gas
(2DEG)
[17]
at interfaces, which is the motivation behind our
work. However, so far BAO combined with half-metallic
ferromagnetic LSMO as multifunctional heterostructures,
have not been reported, especially under e xternal magnetic
fields. In this paper, we focus on the variation tendencies of
resistance, dielectric, and polarization properties of the BA O/
LSMO heterostructure under magnet ic field in different
temperature regions. The result s will open a broad perspective
that BAO/LSMO heterostructures are used for functional
microelectronic devices, and give useful guidelin es to analyze
the magnetic effects on different art ificial multiferroic
heterostructures more deeply.
The LSMO target was prepared by solid state reaction
technique, and BAO target was purchased commercially,
respectively. The ferroelectric BAO (top layer, 80 nm) and
ferromagnetic LSMO (bottom layer, 20 nm) layers were
successively deposited on LAO (111) substrate by pulse laser
deposition technology (PLD), and the detailed deposition process
has been described in our previous report.
[15]
For electrical measurements, Top electrodes Pt were sputtered
on surface by magnetron sputtering at RT, and subsequently
annealed for 5 min at 673 K. The resistance and dielectric
properties of the sample were measured using a 6487 Keithley
electrometer and an Agilent 4980E LCR meter in the
temperature region from 20 to 300 K. The ferroelectric hysteresis
loops (P–E) and magnetic hysteresis loops (M–H) of the
heterostructure were, respectively, performed by ferroelectric
test systems (Precision LC, Radiant Technologies Inc., USA) and
superconducting quantum interference device (SQUID) in the
Prof. C. Chen, Dr. Y. Zhao, Prof. B. Luo,
Prof. H. Xing, Prof. J. Wang, Prof. K. Jin
Shaanxi Key Laboratory of Condensed Matter
Structures and Properties, Northwestern
Polytechnical University, Xi’an 710072, P.R. China
E-mail: chenchl@nwpu.edu.cn
Dr. Y. Zhao
College of Engineering Management, Shaanxi
Radio and Television University, Xi’an 710019,
P.R. China
The ORCID identification number(s) for the author(s) of this article
can be found under https://doi.org/10.1002/pssr.201700155.
DOI: 10.1002/pssr.201700155
Magnetoelectric Coupling www.pss-rapid.com
RAPID RESEARCH LETTER
Phys. Status Solidi RRL 2017, 1700155 © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim1700155 (1 of 5)
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