Sustainable Poetry: Four American Ecopoets

Focusing on the work of A.R. Ammons, Wendell Berry, W.S. Merwin, and Gary Snyder, author Leonard Scigaj shows that just as a sustainable society does not depreciate its resource base, so a sustainable poetry does not restrict interest to language. Over the past thirty years many poets have shown an increasing sensitivity to ecological thinking. But critics trained in poststructuralist language theory often fail to explore the substance of ecopoetry. Scigaj is the first to define ecopoetry as separate and distinct from nature or environmental poetry, marked by its concern with balancing the interests of human beings with the needs of nature. Just as science learned that the earth was not the center of the universe, ecopoetry insists on the recognition that humans are not at the center of the natural world. The first book to treat the US’s four foremost ecopoets as ecopoets. -- Choice Scigaj uses his examination of contemporary ecological poetry to mount a direct assault on the way literary theory has been conducted over the past twenty years. -- Interdisciplinary Studies in Literature and Environment Will join John Elder\u27s Imagining the Earth as the most important contribution to date to the study of contemporary ecopoetry. -- Lawrence Buell A rich context for our understading the work and persons of A.R. Ammons, Wendell Berry, W.S. Merwin, and Gary Snyder, four outstanding American poets. -- Psychological Reports Anyone who things that nature poetry is a leftover mode from a bygone era, or that all nature poets are alike, needs to read this book before we have no nature left. -- Virginia Quarterly Review Urges readers to distinguish between two kinds of poetry in order to set the stage for an epic intellectual and aesthetic battle. -- Western American Literaturehttps://uknowledge.uky.edu/upk_english_language_and_literature_north_america/1001/thumbnail.jp

Yttria-stabilized zirconia/SrTiO_(3) oxide heteroepitaxial interface with symmetry discontinuity

We show that yttria-stabilized zirconia (YSZ) films deposited on structurally dissimilar SrTiO_(3)(110) substrates exhibit two-dimensional layer-by-layer growth. We observed that, up to a thickness of about 15 nm, the square (001) basal plane of the cubic YSZ grows epitaxially on the rectangular (110) crystallographic plane of SrTiO3 substrates, with [110]YSZ(001)//[001]SrTiO_(3)(110) epitaxial relationship. Thus, the heterointerface presents symmetry discontinuity between the YSZ(001) film and the lower surface symmetry SrTiO_(3)(110) substrate. Beyond this specific case, we envisage similar approaches to develop other innovative oxide interfaces showing similar crystal symmetry discontinuities

Competition between polar and nonpolar lattice distortions in oxide quantum wells: new critical thickness at polar interfaces

Two basic lattice distortions permeate the structural phase diagram of oxide perovskites: antiferrodistortive (AFD) rotations and tilts of the oxygen octahedral network and polar ferroelectric modes. With some notable exceptions, these two order parameters rarely coexist in a bulk crystal, and understanding their competition is a lively area of active research. Here we demonstrate, by using the LaAlO₃/SrTiO₃ system as a test case, that quantum confinement can be a viable tool to shift the balance between AFD and polar modes and selectively stabilize one of the two phases. By combining scanning transmission electron microscopy (STEM) and first-principles-based models, we find a crossover between a bulklike LaAlO₃ structure where AFD rotations prevail, to a strongly polar state with no AFD tilts at a thickness of approximately three unit cells; therefore, in addition to the celebrated electronic reconstruction, our work unveils a second critical thickness, related not to the electronic properties but to the structural ones. We discuss the implications of these findings, both for the specifics of the LaAlO₃/SrTiO₃ system and for the general quest towards nanoscale control of material properties

Infrared ellipsometry study of photogenerated charge carriers at the (001) and (110) surfaces of SrTiO3 crystals and at the interface of the corresponding LaAlO3/SrTiO3 heterostructures

2-DIMENSIONAL ELECTRON-GAS; STRONTIUM-TITANATE; PERSISTENT PHOTOCONDUCTIVITY; DOMAIN-STRUCTURE; MOBILITY; TEMPERATURE; TRANSITION; FILMS; GAMMA-AL2O3/SRTIO3; FERROELECTRICITYThe work at the University of Fribourg was supported by the Schweizerische Nationalfonds (SNF) through Grant No. 200020-153660. B.P.P.M. wishes to acknowledge support from the Marsden Fund of New Zealand. The work at MUNI was financially supported by the Ministry of education youth and sports of the Czech Republic, under the project CEITEC 2020 (LQ1601). M.S., F.S., and G.H. acknowledge the support by the Spanish Government through Project No. MAT2014-56063-C2-1-R, the Severo Ochoa Grant No. SEV-2015-0496, and the Generalitat de Catalunya (Project No. 2014SGR 734). J. Mannhart is acknowledged for providing the LAO/STO (001) sample and J. Foncuberta for scientific discussion.Peer reviewe

Infrared ellipsometry study of photogenerated charge carriers at the (001) and (110) surfaces of SrTiO3\mathrm{SrTi}{\mathrm{O}}_{3} crystals and at the interface of the corresponding LaAlO3/SrTiO3\mathrm{LaAl}{\mathrm{O}}_{3}/\mathrm{SrTi}{\mathrm{O}}_{3} heterostructures

With infrared (IR) ellipsometry and dc resistance measurements, we investigated the photodoping at the (001) and (110) surfaces of SrTiO3 (STO) single crystals and at the corresponding interfaces of LaAlO3/SrTiO3 (LAO/STO) heterostructures. In the bare STO crystals, we find that the photogenerated charge carriers, which accumulate near the (001) surface, have a similar depth profile and sheet carrier concentration as the confined electrons that were previously observed in LAO/STO (001) heterostructures. A large fraction of these photogenerated charge carriers persist at low temperature at the STO (001) surface even after the ultraviolet light has been switched off again. These persistent charge carriers seem to originate from oxygen vacancies that are trapped at the structural domain boundaries, which develop below the so-called antiferrodistortive transition at T∗=105K. This is most evident from a corresponding photodoping study of the dc transport in STO (110) crystals for which the concentration of these domain boundaries can be modified by applying a weak uniaxial stress. The oxygen vacancies and their trapping by defects are also the source of the electrons that are confined to the interface of LAO/STO (110) heterostructures, which likely do not have a polar discontinuity as in LAO/STO (001). In the former, the trapping and clustering of the oxygen vacancies also has a strong influence on the anisotropy of the charge carrier mobility. We show that this anisotropy can be readily varied and even inverted by various means, such as a gentle thermal treatment, UV irradiation, or even a weak uniaxial stress. Our experiments suggest that extended defects, which develop over long time periods (of weeks to months), can strongly influence the response of the confined charge carriers at the LAO/STO (110) interface

Untangling electrostatic and strain effects on the polarization of ferroelectric superlattices

The polarization of ferroelectric superlattices is determined by both electrical boundary conditions at the ferroelectric/paraelectric interfaces and lattice strain. The combined influence of both factors offers new opportunities to tune ferroelectricity. However, the experimental investigation of their individual impact has been elusive because of their complex interplay. Here, a simple growth strategy has permitted to disentangle both contributions by an independent control of strain in symmetric superlattices. It is found that fully strained short‐period superlattices display a large polarization whereas a pronounced reduction is observed for longer multilayer periods. This observation indicates that the electrostatic boundary mainly governs the ferroelectric properties of the multilayers whereas the effects of strain are relatively minor

Optical second harmonic generation from LaAlO3/SrTiO3 interfaces with different in-plane anisotropies

Oxide growth with semiconductor-like accuracy allows the fabrication of atomically precise thin films and interfaces displaying a wide range of phases and functionalities that are absent in the corresponding oxide bulk materials. Among the other properties it was found that a two-dimensional electronic gas is formed under some circumstances at the LaAlO3/SrTiO3(0 0 1) interface separating two typical insulating perovskite crystals. The origin of this conducting state has been discussed at length, since different doping mechanisms can act in these material systems. Many experimental results point to the so-called polar catastrophe scenario as the principal mechanism driving the formation of the two-dimensional electronic gas. According to this mechanism, the existence of an interfacial polar discontinuity is the key ingredient to drive an electronic reconstruction at the LaAlO3/SrTiO3(0 0 1) interface and the consequent formation of a two-dimensional electron gas. This simple picture has been often questioned by the existence of material systems whose interface are predicted being non-polar according to the simplistic 'ionic' limit but that display an electrical behavior analogous to that of LaAlO3/SrTiO3(0 0 1) interfaces. This is the case of the LaAlO3/SrTiO3(1 1 0), i.e., a LaAlO3/SrTiO3 interface with a different in-plane orientation. It is evident that to solve such kind of controversies a detailed investigation of the polar or non-polar state of these interfaces is needed, although this is not simple for the lack of experimental tools that are specifically sensitive to interfacial polarity. Here we apply Optical Second Harmonic Generation to investigate LaAlO3/SrTiO3 interfaces with different in-plane orientations to bridge this gap. By comparing our results with recent theoretical findings, we will arrive to the conclusion that the real LaAlO3/SrTiO3(1 1 0) interface is strongly polar