Matter and Methods at Low Temperatures

Transcription

1 Matter and Methods at Low Temperatures

2 Frank Pobell Matter and Methods at Low Temperatures Third, Revised and Expanded Edition With 234 Figures, 28 Tables, and 81 Problems 123

3 Professor Dr. Frank Pobell Robert-Diez-Strasse 1 D Dresden Germany Library of Congress Control Number: ISBN Springer Berlin Heidelberg New York ISBN Springer Berlin Heidelberg New York ISBN 2nd Edition Springer Berlin Heidelberg New York This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer. Violations are liable to prosecution under the German Copyright Law. Springer is a part of Springer Science+Business Media. springer.com Springer-Verlag Berlin Heidelberg 1992, 1996, 2007 The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Typesetting by author and SPi using a Springer LT A EX macro package. Cover design: estudio Calamar S.L., E Girona, Spain Printed on acid-free paper SPIN /3100/SPi

4 Preface to the Third Edition Success of a product is determined by the market. I am therefore very pleased that the first two editions of this book have been sold out, and that the publisher has asked me to work on a third, revised and expanded edition. Obviously, there is still demand for Matter and Methods at Low Temperatures, even almost 15 years after publication of the first edition. Before working on this revision, I had written to more than 20 expert colleagues to ask for their recommendations for revisions. Besides details, the essence of their response was the following (1) Essentially, leave as it is; (2) Add more information on properties of materials at T>1 K; (3) Add information on suppliers of low-temperature equipment. Besides following the latter two recommendations, I have, of course, taken into account all relevant new information and new developments that have become available since the second edition was written more than 10 years ago, in I have found this information in particular in the journals Journal of Low Temperature Physics, Review of Scientific Instruments, and Cryogenics, as well as in the Proceedings of the International Conferences on Low Temperature Physics, which took place in Prague (1996), Helsinki (1999), Hiroshima (2002), and Orlando, FL (2005), as well as of the International Symposium on Quantum Fluids and Solids, which took place in Ithaca, NY (1995), Paris (1997), Amherst, MA (1998), Minneapolis, MN (2000), Konstanz (2001), Albuquerque, NM (2003), and Trento (2004); the latter proceedings have also been published as issues of the Journal of Low Temperature Physics. I have included new chapters or sections on: Closed-cycle refrigerators Methods to measure heat capacity, thermal expansion, and thermal conductivity Magnetic properties of some selected materials (replacing the former short appendix) and methods to measure them The new temperature scale PLTS 2000 (replacing the former section on the preliminary scale CTS-2) and the new superconducting fixed-point device SRD 1000

5 VI Preface Oxide compound resistance thermometers Coulomb blockade thermometry Torsional and translational oscillators Low-temperature electronics, in particular SQUIDs (mostly a summary on the relevant literature) As well as a list of commercial suppliers of cryogenic equipment and materials needed for low-temperature research. Furthermore, I have strongly revised or expanded the sections on dilution refrigeration, pressure transducers, cold valves, small superconducting and normal conducting magnets, on thermometry, in particular resistance, paramagnetic and NMR thermometry, as well as electronic microrefrigerators. The new edition also contains more data on properties of materials at low temperatures. There are still further domains of increasing importance in lowtemperature research and technology that I could have included. For example, the exciting developments on magneto-optically trapped and laser as well as evaporatively cooled highly diluted gases and their Bose Einstein condensation (however, the book still is on condensed-matter physics only); application of low-temperature technology in space research and for particle detection; low-temperature research in very high magnetic fields (partly covered in the sections on calorimetry and on thermometry); or the developments of various scanning tunneling microscopes for applications at low temperatures. These developments show the increasing importance of low temperatures in fields outside of the formerly traditional low-temperature research. However, including them would have surely made this a too voluminous book. It already contains 45 new figures and about 250 additional references compared to the second edition! I am grateful to A. Bianchi, G. Eska, P. Esquinazi, J. Pekola, R. Rosenbaum, K. Uhlig, A.T.A.M. de Waele, as well as W. Buck and his colleagues at the PTB Berlin for reading and commenting on various parts of my manuscript. Last but not least, it is a pleasure for me to acknowledge my close collaboration with Thomas Herrmannsdörfer for about one and a half decades, which has surely contributed to my understanding and appreciation of several areas covered in this book. Dresden August 2006 F. Pobell

6 Preface to the Second Edition It has been a great pleasure for me to see this book very often several copies in almost every low-temperature laboratory I have visited during the past three years. Low- and ultralow-temperature physics continue to be lively and progressing fields of research. New results have emerged over the four years since publication of the first edition of my monograph. The second edition contains relevant results particularly on thermometry and materials properties, as well as many additional references. Of course, typographical errors I had overlooked are now corrected. I am grateful to J. Friebel for checking and solving the problems I have included in this new edition. And, as for the case of the first edition, I again thank H. Lotsch for the very careful editing. I hope that this lower-priced paperback edition will continue to be a valuable source for the research and study of many of my colleagues and their students. Bayreuth November 1995 F. Pobell

7 Preface to the First Edition The aim of this book is to provide information about performing experiments at low temperatures, as well as basic facts concerning the low-temperature properties of liquid and solid matter. To orient the reader, I begin with chapters on these low-temperature properties. The major part of the book is then devoted to refrigeration techniques and to the physics on which they are based. Of equal importance, of course, are the definition and measurement of temperature; hence low-temperature thermometry is extensively discussed in subsequent chapters. Finally, I describe a variety of design and construction techniques which have turned out to be useful over the years. The content of the book is based on the three-hour-per-week lecture course which I have given several times at the University of Bayreuth between 1983 and It should be particularly suited for advanced students whose intended masters (diploma) or Ph.D. subject is experimental condensed matter physics at low temperatures. However, I believe that the book will also be of value to experienced scientists, since it describes several very recent advances in experimental low-temperature physics and technology, for example, new developments in nuclear refrigeration and thermometry. My knowledge and appreciation of low-temperature physics have been strongly influenced and enhanced over the years by many colleagues. In particular, I wish to express my thanks to my colleagues and coworkers at the Institut für Festkörperforschung, Forschungszentrum Jülich and at the Physikalisches Institut, Universität Bayreuth. Their enthusiasm for lowtemperature physics has been essential for the work in our groups, and for many achievements described in this book. Among them I wish to mention especially R.M. Mueller, Ch. Buchal and M. Kubota from the time at Jülich ( ), K. Gloos, R. König, B. Schröder-Smeibidl, P. Smeibidl, P. Sekowski, and E. Syskakis in Bayreuth (since 1983). Above all, I am deeply indebted to my colleague and friend Girgl Eska, who shares with me all the joys and sorrows of our low-temperature work in Bayreuth. He and Bob Mueller read the entire manuscript and made many important comments on it. I am also very grateful to Dierk Rainer for so often

8 X Preface sharing with me his deep insight into the physics of many low-temperature phenomena. It is a pleasure for me to thank Mrs. G. Pinzer for her perfect typing of the manuscript and Ms. D. Hollis for her careful copy-editing. Likewise, I gratefully acknowledge the very thorough and time-consuming checking of the whole manuscript by Dr. H. Lotsch. Finally, I thank the Institute for Physical Problems, USSR Academy of Sciences, where part of the manuscript was written, for the hospitality extended to me, and the Volkswagen Stiftung for a stipend which I held for some time while writing this book. Bayreuth September 1991 F. Pobell

9 Contents 1 Introduction Properties of Cryoliquids Liquid Air, Liquid Oxygen, Liquid Nitrogen Liquid Hydrogen LiquidHelium SomePropertiesoftheHeliumIsotopes Latent Heat of Evaporation and Vapour Pressure SpecificHeat Transport Properties of Liquid 4 He: Thermal Conductivity and Viscosity SuperfluidFilmFlow Liquid 3 He and 3 He 4 He Mixtures at Millikelvin Temperatures Problems Solid Matter at Low Temperatures SpecificHeat Insulators Metals Superconducting Metals Non-Crystalline Solids MagneticSpecificHeat The Low-Temperature Specific Heat of Copper andplatinum Specific Heat of Some Selected Materials Calorimetry or How to Measure Heat Capacities ThermalExpansion ThermalExpansionofSolids Dilatometers or How to Measure ThermalExpansions... 61

10 XII Contents 3.3 Thermal Conductivity Lattice Conductivity: Phonons Electronic Thermal Conductivity Thermal Conductivity at Low Temperatures Superconducting Metals Relation Between Thermal and Electrical Conductivity: The Wiedemann Franz Law Influence of Impurities on Conductivity Thermal Conductivities of Copper, Silver andaluminumatlowtemperatures How to Measure Thermal Conductivities Magnetic Susceptibilities Magnetic Susceptibilities of Some Selected Materials How to Measure Susceptibilities andmagnetizations Problems Thermal Contact and Thermal Isolation Selection of the Material with the Appropriate Cryogenic Thermal Conductivity HeatSwitches GaseousandMechanicalHeatSwitches Superconducting Heat Switches Thermal Boundary Resistance Boundary Resistance Between Metals Boundary Resistance Between Liquid Helium andsolids Problems Helium-4 Cryostats and Closed-Cycle Refrigerators Use of Liquid 4 HeinLow-TemperatureEquipment Cool-DownPeriod Running Phase of the Experiment Helium-4Cryostats Double-WalledGlassDewars MetalDewars Cryostats for T>5K Cryostats with Variable Temperature for 1.3K T 4.2K Auxiliary Equipment Closed-CycleRefrigerators TemperatureControl Problems...137

11 Contents XIII 6 Helium-3 Cryostats Helium-3CryostatswithExternalPumps Helium-3 Cryostats with Internal Adsorption Pumps Problems The 3 He 4 He Dilution Refrigerator Properties of Liquid 3 He 4 HeMixtures Phase Diagram and Solubility He 4 HeMixturesasFermiLiquids Finite Solubility of 3 He in 4 He Cooling Power of the Dilution Process Osmotic Pressure Realization of a 3 He 4 HeDilutionRefrigerator Properties of the Main Components of a 3 He 4 HeDilutionRefrigerator Mixing Chamber Still HeatExchangers Examples of 3 He 4 HeDilutionRefrigerators Problems Refrigeration by Solidification of Liquid 3 He: Pomeranchuck Cooling Phase and Entropy Diagrams of 3 He Entropies of Liquid and Solid 3 He PomeranchukCooling Problems Refrigeration by Adiabatic Demagnetization of a Paramagnetic Salt ThePrincipleofMagneticRefrigeration ThermodynamicsofMagneticRefrigeration Non-Interacting Magnetic Dipoles in a Magnetic Field Paramagnetic Salts and Magnetic Refrigerators Problems Refrigeration by Adiabatic Nuclear Demagnetization Some Equations Relevant for Nuclear Refrigeration Differences in Nuclear and Electronic Demagnetization Interaction Between Conduction Electrons and Nuclei Electron PhononCoupling Nucleus ElectronCoupling Influence of an External Heat Load andtheoptimumfinalmagneticfield...228

12 XIV Contents 10.5 HeatLeaks ExternalHeatLeaks Eddy Current Heating Internal, Time-Dependent Heat Leaks Heating from Radioactivity andhigh-energyparticles NuclearRefrigerants Hyperfine Enhanced Nuclear Refrigeration NuclearDemagnetizationRefrigerators Problems Temperature Scales and Temperature Fixed Points ThermodynamicTemperature TheInternationalTemperatureScaleITS The New Provisional Low-Temperature Scale PLTS Practical but not Officially Accepted Low-Temperature FixedPoints Fixed Points of EPT The NBS Superconducting Fixed-Point Device The SRD 1000 Superconducting Fixed-Point Device The Superfluid Transition of Liquid 4 He Problems Low-Temperature Thermometry GasThermometry Helium Vapour Pressure Thermometry Helium Melting Pressure Thermometry Thermoelectricity ResistanceThermometry Metals Doped-Germanium and Carbon Resistors Oxide Compounds: RuO 2 and Cernox Thermometers ResistanceBridges CoulombBlockadeThermometry NoiseThermometry CapacitanceThermometry Magnetic Thermometry with Electronic Paramagnets Magnetic Thermometry with Nuclear Paramagnets Non-Resonant, Integral Detection of Nuclear Magnetization Selective Excitation but Non-Resonant Detection ofnuclearmagnetization...331

13 Contents XV Resonant Excitation and Resonant Detection ofnuclearmagnetization Magnetic Thermometry via Anisotropy of Gamma Rays Summary Problems Miscellaneous Cryogenic Devices and Design Aids Cryogenic Pressure Transducers forthermometryandmanometry Capacitive Pressure Transducers Inductive Pressure Transducers ColdValves CoaxialCablesandFeedthroughs SmallMagnetsandMagnetLeads Small Superconducting Magnets and Magnet Leads Small Pulsed Normal-Conducting Magnets Shielding Against Magnetic Fields andmagneticfieldsinsideofshields Normal-Conducting Shields Superconducting Shields MagneticFieldsInsideofShields SinteredMetalHeatExchangers Low-TemperatureMotorsandRotators OpticalExperimentsatLowTemperatures Electronic Tunnel-Junction Refrigerators Torsional and Translational Oscillators VibratingReeds VibratingWires QuartzTuningForks Double-Paddle Oscillators Composite Torsional Oscillators Purification of 3 He from 4 He Impurities, and Vice Versa Problems Some Comments on Low-Temperature Electronics List of Symbols ConversionFactors Suppliers of Cryogenic Equipment and Materials References Index...447