Welcome to Yamada group
Alumni meeting
1st alumni meeting of Nagasaki-Yamada lab. was held on Nov. 23rd.
Seminar: Prof. Guorong Li, Dr. Lei Meng, Dr. Xueyou Yuan
On Jul. 18, Prof. Guorong Li (Shanghai Institute of Ceramics) visited us and lectured on high-entropy ferroelectric ceramics. In addition, Dr. Lei Meng and Dr. Xueyou Yuan gave their seminars.
1) Fabrication and Properties of ABO3 Ferroelectric Ceramics with A- and B-site disorder for high-energy storage (Prof. Guorong Li)
2) Strong Second-order Nonlinear-polarization in Widegap ZnMgO Thin-films with Li Incorporation (Dr. Lei Meng)
3) Extraordinarily Large Extrinsic Contribution Ratio to Piezo-response in Monoclinic (K, Na)NbO3 Epitaxial Films (Dr. Xueyou Yuan)
Published: Ferroelectric Freestanding Hafnia Membranes with Metastable Rhombohedral Structure down to 1-nm-thick
Our collaborative paper with Kyoto University entitled “Ferroelectric Freestanding Hafnia Membranes with Metastable Rhombohedral Structure down to 1-nm-thick” has been published in Nat. Commun. We fabricated stable 1-nm-thick hafnia membranes exhibiting the metastable rhombohedral structure and out-of-plane ferroelectric polarizations as large as 13 μC/cm2.
Citation: NC 15, 1055196 (2024).
Seminar: Dr. Alexandros Emborasa
On Jun. 6, Dr. Alexandros Emborasa (ETH Zurich) visited us and lectured on neuromorphic computing.
Lecturer: Dr. Alexandros Emborasa (ETH Zurich)
Seminar title: Neuromorphic Computing: From Devices to Applications
Published: Novel Route for Enhancing Piezoelectricity of Ferroelectric Films: Controlling Nontrivial Polarization States in Pb(Zr, Ti)O3 Monodomain Superlattice Structure
Our paper entitled “Novel Route for Enhancing Piezoelectricity of Ferroelectric Films: Controlling Nontrivial Polarization States in Pb(Zr, Ti)O3 Monodomain Superlattice Structure” has been published in ACS Appl. Mater. Interfaces. We found that (111)-epitaxial artificial superlattice thin films consisting of Pb(Zr0.4Ti0.6)O3 and Pb(Zr0.6Ti0.4)O3 can be stabilized into unique monodomain state, which results in the piezoelectric response larger than the typical clamped films with the same chemical compositions.
Citation: ACSAMI 16, 16145 (2024).
Published: Extraordinarily Large Contribution Ratio of Ferroelastic Domain Switching to Piezoresponse in Monoclinic (K, Na)NbO3 Films
Our paper entitled “Extraordinarily Large Contribution Ratio of Ferroelastic Domain Switching to Piezoresponse in Monoclinic (K, Na)NbO3 Films” has been published in Adv. Electron. Mater. We found that the extrinsic contribution to the piezoresponse in (111)epitaxial monoclinic (K, Na)NbO3 films is extraordinarily large, over 100% under moderate electric fields.
Citation: AEM 10, 2300405 (2024).
Published: Dynamic Electrical Response of Vortex Polarization in PST/STO Superlattice Thin Films
Our paper entitled “Dynamic Electrical Response of Vortex Polarization in (Pb0.9Sr0.1)TiO3/SrTiO3 Artificial Superlattice Thin Films” has been published in Appl. Phys. Lett. We found that the reorientation of dipole moments in the vortex domains is susceptible to the applied electric field pulses of 500 μs and is a reversible process. Although the centrosymmetric vortex domain structure is not considered to exhibit piezoelectricity, an evident change in the out-of-plane lattice constant with the applied electric field was revealed.
Citation: APL 121, 172904 (2022).
Published: Strong Electro-optic Effect in Mg Incorporated ZnO Thin Films
Our paper entitled “Strong Electro-optic Effect in Mg Incorporated ZnO Thin Films” has been published in Appl. Phys. Lett. We found that the Mg incorporation enhances the linear EO response significantly. In particular, the Zn0.72Mg0.28O thin film showed an effective EO coefficient of 7.6 pm/V, which is over three times larger than the reported values for ZnO-based thin films and over twice larger than that of ZnO single crystals. This study is the collaborative research with Dr. Meng of Institute of Semiconductors, Chinese Academy of Sciences.
Citation: APL 121, 152903 (2022).
Published: Ni Doping Effect on the Electro-optic Property in K(Ta, Nb)O3 Films
Our paper entitled “Effect of Ni Doping on the Electro-optic Property in K(Ta0.6Nb0.4)O3 Films” has been published in Jpn. J. Appl. Phys. We found that a larger withstand electric field was achieved by Ni doping, therefore, the variation of refractive index by the applicable maximum electric field was increased.
Citation: JJAP 61, SN1005 (2022).