LABORTORY FOR DIFFRACTION, MAGNETOMETRY AND MAGNETIC RESONANCES
Learning outcomes of the course unit
The course objectives are:
- Learn the fundamentals of some important experimental techniques.
- Learn the principles of operation the scientific instrumentation.
- Gain knowledge of important auxiliary practical techniques to experimental physics (eg. cryogenics, vacuum techniques, conditioning of electrical signals).
- Acquire an experimental sensitivity and promote the autonomous design of an experiment.
- Develop a critical sense with respect to the results obtained, making it possible to analyze and properly present the experimental data, with appropriate methodologies and software tools.
- Teaching to keep a good conduct in laboratory.
None, besides skills and knowledge acquired during the bachelor (electromagnetism, geometrical optics and classical wave, quantum mechanics, condensed matter physics).
Course contents summary
The course aims to introduce the students to the experimental techniques of powder X-ray diffraction, solid state nuclear magnetic resonance and magnetometry, which are essential tools for the study and the physical characterization of the materials. The course is divided into laboratory sessions, that will be introduced by recalling the fundamentals underlying the different techniques. During the experimental activity, the students will take familiarity with the measuring instruments, by the investigation of the properties of selected materials.
The course is divided in three experiments: X-ray powder diffraction (PXRD), solid state nuclear magnetic and/or quadrupole resonance (NMR/NQR) and stationary pendulum magnetometry, held at the homonymous research laboratories of the Department of Physics and Earth Sciences.Each experiment is preceded by short introductory lectures cycles, which intend to provide the students with the basics knowledge and the operation principles of the instrumentation used. In the following you can find the details of the topics:
- Laboratory of X-ray diffraction: Kinematic theory of diffraction, symmetry in crystals, interference of waves scattered by a crystal, the structure factor, the Debye-Waller factor, X-ray sources, X-ray detectors, powder diffraction, corrections and analysis of diffraction data, Rietveld refinement. Acquisition of diffraction patterns will be done by a Bruker D8 Discover diffractometer, even as a function of temperature, using appropriate software for data analysis (GSAS suites).
- Nuclear magnetic resonance Laboratory: experimental techniques for magnetism, nuclear magnetic resonance in magnetic materials, hyperfine coupling, crystal field, enhancement, nuclear magnetic resonance in manganites, the NMR spectrometer. Nuclear magnetic resonance measurements on manganites will be performed in the absence and in the presence of external magnetic field, by the use of cryogenic techniques.
- Laboratory of magnetometry: magnetism in condensed matter, origin of the atomic magnetism, diamagnetism, paramagnetism, magnetically ordered states, experimental techniques. The measurement of the magnetic response of materials will be performed by means of a stationary pendulum magnetometer Manics DSM-8.
- Charles Kittel, "Introduzione alla fisica dello stato solido", Casa editrice ambrosiana
- G. Giacovazzo, H. L. Monaco, D. Viterbo, F. Scordari, G. Gilli, G. Zanotti and M. Catti, "Fundamentals of Crystallography", C. Giacovazzo ed.
- B. E. Warren, "X-ray diffraction", Dover Publications ed.
- C. P. Slichter, "Principles of magnetic resonance", Springer-Verlag ed.
- M. H. Levitt, "Spin Dinamics: basis of magnetic resonance", Wiley and Sons ed.
- K. H. J. Buschow, F. R. De Boer, "Physics of magnetism and magnetic materials", Kluwer Acad. Publ.
- S. Blundell, "Magnetism in condensed matter", Oxford University press.
Laboratory experimental sessions accompanied by the constant presence of the teacher, which are introduced by lectures, to recall the fundamentals of techniques.
During the health emergency due to the Coronavirus, lessons will be carried out: 1) in "mixed" mode, namely with laboratories and lessons in presence (in small groups, with the use of appropriate PPE), but also with the availability of frontal lessons in remote, in synchronous / asynchronous mode; 2) if the emergency does not allow the presence, both the laboratory sessions and the frontal sessions will be carried out remotely, in synchronous
/asynchronous mode. The remote modality will take place through the Microsoft Teams software and the teaching material will be uploaded on the Elly platform.
Assessment methods and criteria
The exam takes place already during the laboratory sessions. At the end of each experiment and before starting the next one, the student is asked to submit a report, in which they are presenting in a clear, concise and complete way: the goal of the experiment, the relevant physics for understanding the experiment, the instrumentation used, the experimental data properly analyzed and the conclusions. The exam consists of an interview dealing with the discussion of the reports.
During the health emergency due to the Coronavirus, the oral interview will be conducted remotely via the Microsoft Teams platform.
Depending on the availability of the host laboratory, it is tentatively given students the opportunity to carry out or continue the experiments also at times other than those provided, due to specific needs of the student (eg. in the case of student-workers) or to the measure (for eg. long measures extending to the next day).