[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. DSC research groups have been established around the worl ...

/pdf/dye-sensitized-solar-cells-50b0w2bhsr.pdf

Dye-Sensitized Solar Cells

BiFeO3 is perhaps the only material that is both magnetic and a strong ferroelectric at room temperature. As a result, it has had an impact on the field of multiferroics that is comparable to that of yttrium barium copper oxide (YBCO) on superconductors, with hundreds of publications devoted to it in the past few years. In this Review, we try to summarize both the basic physics and unresolved aspects of BiFeO3 (which are still being discovered with several new phase transitions reported in the past few months) and device applications, which center on spintronics and memory devices that can be addressed both electrically and magnetically.

Physics and Applications of Bismuth Ferrite

Multiferroic magnetoelectric materials, which simultaneously exhibit ferroelectricity and ferromagnetism, have recently stimulated a sharply increasing number of research activities for their scientific interest and significant technological promise in the novel multifunctional devices. Natural multiferroic single-phase compounds are rare, and their magnetoelectric responses are either relatively weak or occurs at temperatures too low for practical applications. In contrast, multiferroic composites, which incorporate both ferroelectric and ferri-/ferromagnetic phases, typically yield giant magnetoelectric coupling response above room temperature, which makes them ready for technological applications. This review of mostly recent activities begins with a brief summary of the historical perspective of the multiferroic magnetoelectric composites since its appearance in 1972. In such composites the magnetoelectric effect is generated as a product property of a magnetostrictive and a piezoelectric substance. A...

Multiferroic magnetoelectric composites: Historical perspective, status, and future directions

R J Baxter 1982 London: Academic xii + 486 pp price £43.60 Over the past few years there has been a growing belief that all the twodimensional lattice statistical models will eventually be solved and that it will be Professor Baxter who solves them. Baxter has inherited the mantle of Onsager who started the process by solving exactly the two-dimensional Ising model in 1944.

Exactly Solved Models in Statistical Mechanics

A series of manganites Tb(1-x) Ho (x) MnO(3) (0a parts per thousand currency signxa parts per thousand currency sign0.6) with orthorhombic structure are synthesized and detailed investigations on their multiferroicity are performed. Successive magnetic transitions upon temperature variation are evidenced for all the samples, and both the Mn(3+)spiral spin ordering and rare-earth spin ordering are suppressed with increasing x. A significant enhancement of both the polarization and magnetoelectric response within 0.2 < x < 0.4 is observed, which may probably result from the shortening of the spiral-spin-ordering period, due to the competition between the spiral spin order and E-type antiferromagnetic order. This argument is supported by further theoretical calculations based on the two e (g) -orbital double-exchange model.

Enhanced polarization and magnetoelectric response in Tb 1− x Ho x MnO 3

Epitaxial orthorhombic YMnO3(YMO) thin films on (001) Nb:SrTiO3(NSTO) substrates were prepared by pulsed laser deposition. The weak ferromagnetism at low temperature, probably ascribed to the stretched Mn-spin configuration along [010] direction, was identified. The dielectric anomaly at the spin–glass freezing point indicates clearly a spin–phonon (magnetoelectric) coupling which can be modulated by electric field. The as-prepared YMO/NSTO heterostructure exhibits significant current–voltage (I–V) rectifying effect over a broad temperature range.

Preparation of epitaxial orthorhombic YMnO 3 thin films and the current–voltage rectifying effect

The dielectric and ferroelectric behaviors of relaxor ferroelectrics over the ferroelectric transition range are simulated using Monte Carlo simulation. The simulation is based on the Ginzburg-Landau ferroelectric model lattice in which a random distribution of two types of defects (dopants) which will suppress and enhance the local polarization, respectively, is assumed. The simulation reveals an evolution of the ferroelectric transitions from a normal first-order mode toward a diffusive mode, with increasing defect concentration. The simulated lattice configuration shows the microdipole ordered clusters embedded in the matrix of paraelectric phase over a wide range of temperature, a characteristic of relaxor ferroelectrics. The relaxor-like behaviors are confirmed by the lattice free energy, dielectric susceptibility, and ferroelectric relaxation evaluated as a function of the defect concentration. Finally, we present a qualitative comparison of our simulated results with the simulation based on the coarse-grain model [C. C. Su, B. Vugmeister, and A. G. Khachaturyan, J. Appl. Phys. 90, 6345 (2001)]. (C) 2004 American Institute of Physics.

/pdf/monte-carlo-simulation-on-dielectric-and-ferroelectric-165d1d78ib.pdf

Monte Carlo simulation on dielectric and ferroelectric behaviors of relaxor ferroelectrics

Charge dipole moment and spin moment rarely coexist in single-phase bulk materials except in some multiferroics. Despite the progress in the past decade, for most multiferroics their magnetoelectric performance remains poor due to the intrinsic exclusion between charge dipole and spin moment. As an alternative approach, the oxide heterostructures may evade the intrinsic limits in bulk materials and provide more attractive potential to realize the magnetoelectric functions. Here we perform a first-principles study on LaAlO$_3$/PbTiO$_3$ superlattices. Although neither of the components is magnetic, magnetic moments emerge at the ferroelectric domain walls of PbTiO$_3$ in these superlattices. Such a twist between ferroelectric domain and local magnetic moment, not only manifests an interesting type of multiferroicity, but also is possible useful to pursuit the electrical-control of magnetism in nanoscale heterostructures.

Ferroelectricity driven magnetism at domain walls in LaAlO$_3$/PbTiO$_3$ superlattices

In this work, Sm and Sc co-doped Bi1−x Sm x Fe1−y Sc y O3 (x = 0.00–0.20; y = 0.03) ceramics are fabricated by a rapid liquid phase sintering method, in order to develop single-phase multiferroics with large magnetization and polarization. X-ray diffraction and Raman spectroscopic studies reveal that the ceramics are single-phase with a structural transition from rhombohedral to orthorhombic structures near x = 0.15. Electric and magnetic measurement results indicate that the transition significantly enhances the multiferroic properties, which stems from the Sm/Sc doping induced collapse of space-modulated spin structure and internal structural distortion. At an optimized composition of Bi0.85Sm0.15Fe0.97Sc0.03O3 (x = 0.15), a remanent polarization of 16.5 μC cm−2, a magnetization 0.2020 emu g−1, and a magnetodielectric effect of 0.46% can be obtained. These results clearly demonstrate a potential application for Sm/Sc doped BiFeO3 ceramics in the field of multiferroic devices.

https://iopscience.iop.org/article/10.1088/0022-3727/48/39/395302/pdf

J.-M. Liu

Papers

Enhanced polarization and magnetoelectric response in Tb 1− x Ho x MnO 3

Preparation of epitaxial orthorhombic YMnO 3 thin films and the current–voltage rectifying effect

Monte Carlo simulation on dielectric and ferroelectric behaviors of relaxor ferroelectrics

Ferroelectricity driven magnetism at domain walls in LaAlO$_3$/PbTiO$_3$ superlattices

Room temperature multiferroic and magnetodielectric properties in Sm and Sc co-doped BiFeO3 ceramics