Nanomagnetism, Javier Tejada

NANOMAGNETISM

Javier Tejada

University of Barcelona

Earth Magnetic Field Magnetotactic Bacterium

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constSLJ

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Einstein in a letter to a student, May 31,1915, (quoted by K. Selig): “Any boy could do the work on magnetism, but the general theory of relativity is quite a different matter.”

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Distribution of sizes

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Cobalt 3nm

FC and ZFC Magnetization Curves

Free Rotors – Rotational Doppler Effect

?detectable L ofon quantizati Is

L/I ,'

Free Rotors - Experiment (Tejada et al., 2010)

Quantum Steps in the Microwave Absorption

:acetate Mn ofy bistabilit Magnetic 12

10 S

ˆˆˆ 2zSD

0],ˆ[ zS crystal acetate Mn12

nm 731.

nm 24.1

nm 731.

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Quantum Magnetization Curve J. Friedman, M. Sarachik, J. Tejada, R. Ziolo (PRL - 1996)

EC and Javier Tejada (Barcelona – Spain)

Milestone 22

(1996) Mesoscopic tunnelling of magnetization

Karl Ziemelis, Chief Editor Physical Sciences, Nature28 February 2008 | doi:10.1038/nphys877

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)/( : Bzmm gDkBEE

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140 mT/s14 mT/s2.8 mT/s

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µ0H(T)

T=40 mK

array of SQUIDs

B

sample

array of SQUIDs

0k

1k

2k

m = 1 to m = 2 transition: f = 0.08 THz

m = 9 to m = 10 transition: f = 0.35 THz

12Mn

Experiment: J. Tejada, E. M. Chudnovsky, J.-M. Hernandez, R. Amigo (2003)

Avalanches in Mn-12 Acetate

Magnetic Deflagration (Chudnovsky et al - 2005)

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BUv

2

)(exp

2/1

0

Quantum Magnetic Deflagration [Tejada et al - 2005]

Lectures on Magnetism(with 128 Problems)  

Eugene M. ChudnovskyJavier Tejada

Rinton Press

Lectu

res on M

agnetism

with 128 P

roblems  

Lectures on Magnetismwith 128 Problems

This book is intended as a compact one-semester course for graduate and upper-level undergraduate students. It teaches basic language and ideas that are used by researchers working in the field of magnetism of solids. In selecting the material the preference has been given to simple mathematically rigorous models that explain magnetic phenomena qualitatively. The book consists of three chapters, twenty four sections; each section being accompanied by homework problems. Magnetism at the nanometer scale of individual atoms and molecules is discussed in the first chapter. Magnetic order at the mesoscopic scale of many interacting atoms and itinerant electrons is studied in the second chapter. Magnetism at the macroscopic scale of magnetic domains is considered in the third chapter. The chapters are connected through demonstration of the fact that same magnetic phenomena can be looked at from different angles and described by models that use different techniques. The book should be useful for students who plan to work in condensed matter physics and material science. It can also be of interest to students specializing in other fields because many ideas and methods initially developed to describe magnetism of solids subsequently entered other areas of physics.

Visit Rinton Press on the World Wide Web at: http://www.rintonpress.com

E. M

. Ch

ud

novsk

yJ. T

ejada

M

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Domains and domain walls

Topology: Magnetic Skyrmions and Magnetic Instantons

GMR