Some New Properties of Ferroelectrics: THz Emission, Nano-domain Switching, Finite-Size Effects, and Ferroelectrically-induced-Ferromagnetism.
A brief discussion is given of several new topics in ferroelectricity: First, we show that arrays of lead zirconate-titanate (PZT) nanotubes give intense THz emission from 2-8 THz, offering some advantages over semiconductors such as p-InAs [Scott, Banys et al., Nano Lett. (2008 in press)], including the possibility of electrically driven (non-optical) devices. Second, we demonstrate new effects in switching of nano-domains, including vortex ``doughnut" domains and faceting of circular domains [Gruverman et al, J. Phys. Cond. Mat. 20, 342201 (2008); Scott et al., J. Phys. Cond. Mat. (2008 in press); Lahoche et al., Integ. Ferroelec. 99, 60 (2008)]. Third, we examine true finite-size effects in free-standing crystals of ca. 50 micron thickness, making it clear that differences between crystals and ceramic films of such thickness are extrinsic and not due to depolarization fields [Saad, Schilling et al., Integ. Ferroelec. 61, 239 (2004); 92, 53 (2007)]. Finally, we reexamine magnetoelectricity in multiferroics and show that ferroelectrically induced ferromagnetism is possible in antiferromagnets [Fox and Scott, J. Phys. C: Sol. St. Phys. 10, L329 (1977)] but not paramagnets, and that, following Fox et al., the essential term in the free energy is always trilinear, of form PMjLk, where P is polarization, L, sublattice magnetization, and M, weak ferromagnetization [Fox et al., Phys. Rev. B21, 2926 (1980); J. M. Perez-Mato, ESME, Girona (Sept. 2008)]. Bio:James Scott was born in Beverly, NJ in 1942 as the middle child of three in a working class family. Neither his parents nor grandparents went through high school, let alone university. His father was orphaned at an early age and went to work in a coal mine at age 13; his mother, the youngest of 10 children, was blinded in an automobile accident at about the same age. He attended the public high school in Burlington, NJ and was interested in science, including ham radio (K2PPV).At 17 he received a scholarship to Harvard where he majored in physics. After Cambridge he ventured west to Ohio State. He completed his Ph.D. at age 23 under the supervision of Prof. K. Narahari Rao, a man he greatly admired. The thesis was on experimental optics – timely with the concurrent invention of lasers. Immediately afterwards he joined Bell Labs at Murray Hill, working for Sergio Porto on laser Raman spectroscopy of crystals. Over the next six years he emphasized studies of phase transitions and in this way drifted into ferroelectrics. All of his solid-state physics was self-taught (his Ph.D. thesis was in the molecular spectroscopy of acetylene). He benefited greatly by working with Paul Fleury, John Worlock, and Rogerio Leite.At age 29 he was appointed full professor of physics at the University of Colorado, where he remained for more than 20 years. His first postdoc there was John Ryan, now professor of physics at Oxford. While at Colorado he met his wife, Galya, in the office of Pyotr Kapitza in Moscow. They were married in Moscow in 1982 at the peak of the Cold War. Scott's venture into thin films and ferroelectric memories came about through Galya, who was asked to translate a text on ferroelectric thin films by Tomashpolskii for Ramtron Corp. This brought Scott into Ramtron (eventually as Director of the Technical Board) and to close work with Carlos Araujo and Larry McMillan, with whom he later formed Symetrix Corp. The PZT work at Ramtron was done by Scott and others, notably S. Eaton, who was in large part responsible for the ``PUND" method of measuring hysteresis without charge injection artifacts [Scott J F et al., Switching Kinetics of Lead Zirconate Titanate Submicron Thin-Film Memories, JOURNAL OF APPLIED PHYSICS 64: 787-792 (1988)].During his 21 years in Boulder, CO, Scott was awarded both the prize for best classroom teacher (a secret ballot of the students) and the university research award as best researcher (an extra sabbatical, spent in Paris).In 1991 Scott moved to Australia as Dean of Science, first at RMIT (Melbourne) and later at the University of New South Wales (UNSW, Sydney). Although busy as a dean, he continued to publish papers in Nature and other high-impact journals and in 1997 received both a Humboldt Prize from Germany and appointment as the SONY Corporation Chair of Science in Yokohama, where he continued his work on FRAMs (ferroelectric memories).In 1999 he was appointed by invitation Research Professor of Ferroics at Cambridge University, a post he still holds. He received the Monkasho Award from Japan in 2001 and was elected a Fellow of the Royal Society (FRS) in 2008. He has published more than 400 papers, of which ``Ferroelectric Memories" (Science 1989) has 2400 citations.