Download or read book Phase Transitions in Molecule based Magnets written by Carmen R. Kmety-Stevenson and published by . This book was released on 2000 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: The crystallographic and magnetic properties for the M[N(CN)2]2 (M = Mn, Fe, Co, Ni) series have been investigated by neutron diffraction, dc magnetization, ac susceptibility and specific heat on polycrystalline samples. The crystal structures for all compounds are isomorphous in the paramagnetic regime as well as in the ordered state, and consist of discrete octahedra which are axially elongated and successively tilted in the ab-plane. The zero-field magnetic structure for the Mn and Fe compounds consists of two sublattices which are antiferromagnetically coupled and spontaneously canted, with spin orientation mainly along the a-axis. There is a small uncompensated moment along the b-axis (Mn) and the c-axis (Fe). The zero-field magnetic structure for the Co and Ni compounds is collinear ferromagnetic with spin orientation along the c-axis. The results provide the first determination of a complete magnetic structure in the ordered state for a molecule-based magnet. The ground states are characterized by large magnetic anisotropy. The application of a magnetic field induces a spin rotation transition in the Mn compound and an energy-level crossing in the Fe compound. The dc magnetization and in-field specific heat studies for Cu[N(CN)2]2 reveal the previously unknown ferromagnetic ordering at low temperatures. Comparisons of the magnetic structures for the isostructural M[N(CN)2]2 (M = Mn, Fe, Co, Ni) series suggest that the spin direction is stabilized by crystal fields and the spin canting is induced by the successive tilting of the octahedra. We propose that the superexchange interaction is the mechanism responsible for the magnetic ordering in these compounds and we find that a crossover from noncollinear antiferromagnetism to collinear ferromagnetism occurs for a superexchange angle of [alpha]c = 142.0(5)°.
Download or read book Vibrational Properties of Molecule based Multiferroics and Quantum Magnets Across Quantum Phase Transitions written by Kendall Day Hughey and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molecule-based materials offer unique opportunities to explore the interplay between charge, spin, and lattice across quantum phase transitions. With their flexible architectures and overall low energy scales, quantum phases can be induced at experimentally realizable conditions. In this dissertation, I present a spectroscopic study of three important families of multiferroics and quantum magnets with a variety of tuning parameters to unravel the mechanisms required to reach distinct non-equilibrium phases. The exploration of spin-lattice coupling and local lattice distortions across magnetic quantum phase transitions is the unifying theme of this work. As our first platform for investigation, we explore the coupling between ferroic orders in the metal-organic framework [(CH3)2NH2]M(HCOO)3 (M=Mn,Co,Ni) family. The formate bend links the ferroelectric and magnetic quantum phase transition in the Mn analog. Strikingly, B-site substitution drastically alters this mechanism. The Ni material behaves similarly to the Mn analog but at much higher energy scales, whereas the Co system utilizes formate stretches. B-site substitution is thus a powerful tool for developing structure-property relations within chemically analogous materials, providing control of electronic and magnetic properties as well as energy scales. Copper coordination polymers provide a second platform with which to extend our work. Magneto-infrared spectra of [Cu(pyz)2(2-HOpy)2](PF6)2 and [Cu(pyz)1.5(4-HOpy)2](ClO4)2, combined with prior work of other copper complexes, allow for the investigation of spin-lattice coupling across magnetic quantum phase transitions as a function of structural and magnetic dimensionality. Spin-phonon coupling strength versus magnetic dimensionality reveals that coupling is maximized in the ladder complex. These findings are applicable to other materials with field-induced transitions from the antiferromagnetic to fully saturated state. Multiferroic (NH4)2[FeCl5(H2O)] is our final test case, sporting a complex network of hydrogen and halogen bonds. The high-field polarization change is quenched at the quasicollinear- to collinear-sinusoidal magnetic reorientation, collapsing before magnetic saturation. Remarkably, nearly all low-frequency modes distort to facilitate the development of the magnetic quantum phase, entirely different than most other molecule-based magnets. Signatures of electron-phonon coupling emerge through magneto-infrared measurements. Together, these findings elucidate quantum phase transitions, spin-lattice coupling, and structure-property relations in molecular multiferroics and quantum magnets, motivating further exploration of non-equilibrium phases in these materials.
Download or read book Magnetic Resonance of Phase Transitions written by Frank J. Owens and published by Academic Press. This book was released on 2013-10-22 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic Resonance of Phase Transitions shows how the effects of phase transitions are manifested in the magnetic resonance data. The book discusses the basic concepts of structural phase and magnetic resonance; various types of magnetic resonances and their underlying principles; and the radiofrequency methods of nuclear magnetic resonance. The text also describes quadrupole methods; the microwave technique of electron spin resonance; and the Mössbauer effect. Phase transitions in various systems such as fluids, liquid crystals, and crystals, including paramagnets and ferroelectrics, are also considered. Physicists and scientists working in energetic materials laboratories will find the book invaluable.
Download or read book Phase Transitions and Self Organization in Electronic and Molecular Networks written by J.C. Phillips and published by Springer Science & Business Media. This book was released on 2006-04-11 with total page 455 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in nanoscale science show that the properties of many materials are dominated by internal structures. In molecular cases, such as window glass and proteins, these internal structures obviously have a network character. However, in many partly disordered electronic materials, almost all attempts at understanding are based on traditional continuum models. This workshop focuses first on the phase diagrams and phase transitions of materials known to be composed of molecular networks. These phase properties characteristically contain remarkable features, such as intermediate phases that lead to reversibility windows in glass transitions as functions of composition. These features arise as a result of self-organization of the internal structures of the intermediate phases. In the protein case, this self-organization is the basis for protein folding. The second focus is on partly disordered electronic materials whose phase properties exhibit the same remarkable features. In fact, the phenomenon of High Temperature Superconductivity, discovered by Bednorz and Mueller in 1986, and now the subject of 75,000 research papers, also arises from such an intermediate phase. More recently discovered electronic phenomena, such as giant magnetoresistance, also are made possible only by the existence of such special phases. This book gives an overview of the methods and results obtained so far by studying the characteristics and properties of nanoscale self-organized networks. It demonstrates the universality of the network approach over a range of disciplines, from protein folding to the newest electronic materials.
Download or read book Magnetic Phase Transitions In Single Crystals written by Daivd P Belanger and published by World Scientific. This book was released on 2022-07-27 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic crystals are ideal systems to study the universal properties of phase transitions, particularly systems with quenched randomness and frustration. Pure systems with different symmetries provide the foundation for studies in corresponding systems with quenched randomness. Because phenomena near phase transitions have universal properties, results from bulk magnetic crystals provide a basis for understanding phase transitions in films and nanoparticles, as well as many non-magnetic materials.This motivates the subject of this book, which discusses phase transitions studies in magnetic crystals from the perspective of an experimentalist who has done extensive work in the field. The advantage is that many experimental techniques are described in sufficient detail for a good understanding of the results and their comparison to theory.
Download or read book The Physics of Phase Transitions written by Pierre Papon and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Physics of Phase Transitions occupies an important place at the crossroads of several fields central to materials sciences. This second edition incorporates new developments in the states of matter physics, in particular in the domain of nanomaterials and atomic Bose-Einstein condensates where progress is accelerating. New information and application examples are included. This work deals with all classes of phase transitions in fluids and solids, containing chapters on evaporation, melting, solidification, magnetic transitions, critical phenomena, superconductivity, and more. End-of-chapter problems and complete answers are included.
Download or read book Molecular Magnets written by Maria Bałanda and published by MDPI. This book was released on 2019-03-19 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molecular magnets show many properties not met in conventional metallic magnetic materials, i.e. low density, transparency to electromagnetic radiation, sensitivity to external stimuli such as light, pressure, temperature, chemical modification or magnetic/electric fields, and others. They can serve as “functional” materials in sensors of different types or be applied in high-density magnetic storage or nanoscale devices. Research into molecule-based materials became more intense at the end of the 20th century and is now an important branch of modern science. The articles in this Special Issue, written by physicists and chemists, reflect the current work on molecular magnets being carried out in several research centers. Theoretical papers in the issue concern the influence of spin anisotropy in the low dimensional lattice of the resulting type of magnet, as well as thermodynamics and magnetic excitations in spin trimers. The impact of external pressure on structural and magnetic properties and its underlying mechanisms is described using the example of Prussian blue analogue data. The other functionality discussed is the magnetocaloric effect, investigated in coordination polymers and high spin clusters. In this issue, new molecular magnets are presented: (i) ferromagnetic high-spin [Mn6] single-molecule magnets, (ii) solvatomagnetic compounds changing their structure and magnetism dependent on water content, and (iii) a family of purely organic magnetic materials. Finally, an advanced calorimetric study of anisotropy in magnetic molecular superconductors is reviewed.
Download or read book Molecular Magnets written by Juan Bartolomé and published by Springer Science & Business Media. This book was released on 2013-10-17 with total page 401 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides an overview of the physical phenomena discovered in magnetic molecular materials over the last 20 years. It is written by leading scientists having made the most important contributions to this active area of research. The main topics of this book are the principles of quantum tunneling and quantum coherence of single-molecule magnets (SMMs), phenomena which go beyond the physics of individual molecules, such as the collective behavior of arrays of SMMs, the physics of one-dimensional single–chain magnets and magnetism of SMMs grafted on substrates. The potential applications of these physical phenomena to classical and quantum information, communication technologies, and the emerging fields of molecular spintronics and magnetic refrigeration are stressed. The book is written for graduate students, researchers and non-experts in this field of research.
Download or read book Molecular Magnetic Materials written by Barbara Sieklucka and published by John Wiley & Sons. This book was released on 2017-01-17 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive overview of this rapidly expanding interdisciplinary field of research. After a short introduction to the basics of magnetism and molecular magnetism, the text goes on to cover specific properties of molecular magnetic materials as well as their current and future applications. Design strategies for acquiring molecular magnetic materials with desired physical properties are discussed, as are such multifunctional materials as high Tc magnets, chiral and luminescent magnets, magnetic sponges as well as photo- and piezo-switching magnets. The result is an excellent resource for materials scientists, chemists, physicists and crystal engineers either entering or already working in the field.
Download or read book Multifunctional Molecular Magnets Based on Octacyanidometalates written by Kenta Imoto and published by Springer. This book was released on 2017-08-08 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis demonstrates the novel magnetic functionalities in cyanido-bridged metal assemblies, and as such appeals to readers in the field of materials science. The utilization of octacyanidometalates as building blocks enables the observation of (i) photo-induced magnetization due to a light-induced spin-crossover in an iron octacyanidoniobate-based assembly, (ii) photo-induced magnetization with a two-step spin-crossover behavior in an iron octacyanidoniobate-based material, and (iii) the coexistence of super-ionic conductivity and metamagnetism in a manganese-octacyanoniobate system. These multi-functionalities are achieved by incorporating a spin-crossover moiety or a hydrogen-bonding network into a cyanido-bridged network structure with a strong magnetic interaction. In particular, in light-induced spin-crossover magnets, a magnetically non-ordered state can be altered to a magnetically ordered state by photo-irradiation, which is one of the attractive mechanisms for novel optical switching devices.
Download or read book Ferromagnetic antiferromagnetic Phase Transitions written by Thomas James Hendrickson and published by . This book was released on 1956 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Quantum Phase Transitions written by Subir Sachdev and published by Cambridge University Press. This book was released on 2011-04-07 with total page 521 pages. Available in PDF, EPUB and Kindle. Book excerpt: Describing the physical properties of quantum materials near critical points with long-range many-body quantum entanglement, this book introduces readers to the basic theory of quantum phases, their phase transitions and their observable properties. This second edition begins with a new section suitable for an introductory course on quantum phase transitions, assuming no prior knowledge of quantum field theory. It also contains several new chapters to cover important recent advances, such as the Fermi gas near unitarity, Dirac fermions, Fermi liquids and their phase transitions, quantum magnetism, and solvable models obtained from string theory. After introducing the basic theory, it moves on to a detailed description of the canonical quantum-critical phase diagram at non-zero temperatures. Finally, a variety of more complex models are explored. This book is ideal for graduate students and researchers in condensed matter physics and particle and string theory.
Download or read book A Themed Issue of Functional Molecule based Magnets written by Keiichi Katoh and published by MDPI. This book was released on 2020-05-29 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research on molecule-based magnetic materials was systematized in the 1980s and expanded rapidly. A Special Issue focusing on molecule-based magnetic substances was published in Magnetochemistry. However, the functionalities of the substances increase daily; therefore, the researchers’ quest is not yet in decline. Research on molecule-based magnetism developed across many fields, including chemistry, physics, material chemistry, and applied physics, and the use of the various functionalities of these molecule-based magnetic substances has greatly influenced research on spin-based devices. In honor of Professor Masahiro Yamashita, who contributed greatly to this field, I have put together a Special Issue that highlights ten groundbreaking articles. The issue is entitled, “A Themed Issue of Functional Molecule-Based Magnets: Dedicated to Professor Masahiro Yamashita on the Occasion of his 65th Birthday”. I wish to thank the authors for their dedicated work, and the referees and editorial staff for the time they invested commenting on the articles.
Download or read book Molecule based Magnetic Materials written by Mark M. Turnbull and published by . This book was released on 1996 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents a mixture of tutorial chapters on theoretical and practical aspects of molecular magnetism, as well as chapters describing the most recent developments in the field. Provides a comprehensive review of organic molecule-based materials. Includes an introductory section that highlights the theory and instrumental techniques commonly employed in the field. Discusses finite systems such as organic and metal-based dimers, oligomers, and cluster molecules. Describes extended organic systems and extended metal-based systems.
Download or read book Photoinduced Phase Transitions written by Keiichir? Nasu and published by World Scientific. This book was released on 2004 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new class of insulating solids was recently discovered. When irradiated by a few visible photons, these solids give rise to a macroscopic excited domain that has new structural and electronic orders quite different from the starting ground state. This occurrence is called ?photoinduced phase transition?, and this multi-authored book reviews recent theoretical and experimental studies of this new phenomenon.Why and how do photoexcited few electrons finally result in an excited domain with a macroscopic size? How is the resultant photoinduced phase different from the ordinary thermal-induced phase? This review volume answers those essential questions.This book has been selected for coverage in: ? CC / Physical, Chemical & Earth Sciences? Index to Scientific Book Contents? (ISBC)
Download or read book Phase Transitions in Materials written by Brent Fultz and published by Cambridge University Press. This book was released on 2014-08-14 with total page 589 pages. Available in PDF, EPUB and Kindle. Book excerpt: A clear, concise and rigorous textbook covering phase transitions in the context of advances in electronic structure and statistical mechanics.
Download or read book Comprehensive Handbook of Calorimetry and Thermal Analysis written by Michio Sorai and published by John Wiley & Sons. This book was released on 2004-09-03 with total page 570 pages. Available in PDF, EPUB and Kindle. Book excerpt: Publisher Description
