Exercises. 3) Translate the sentences into Russian. Translate the text into English in writing. Вклад Альбера фера и Петера Грюнберга

2) Answer the questions:

a) How did W. Thomson (Lord Kelvin) contribute to studying the phenomenon of magnetoresistance?

b) Can you define anisotropic magnetoresistance (AMR) and giant magnetoresistance (GMR)?

c) What metals did the groups led by Peter Grü nberg and Albert Fert use in their groundbreaking experiments in the 1980s? What did they achieve?

d) Can you describe the resistance of a GMR device?

e) What are half-metals?

f) What is tunneling magnetoresistance?

g) What new field of science did the discovery of GMR lead to?

h) Which new technological possibilities did GMR reveal?

3) Translate the sentences into Russian.

a) Not only did Fert and Grü nberg measure strongly enhanced magnetoresistivities, but they also identified these observations as a new phenomenon, where the origin of the magnetoresistance was of a totally new type.

b) Since magnetoresistance deals with electrical conductivity it is obvious that it is the behaviour of the electrons at the Femi surface (defined by the Fermi energy) which is of primary interest.

c) Here the insulating material should be only a few atomic layers thick so that there is a significant probability that electrons can quantum mechanically tunnel through the insulating barrier.

Translate the text into English in writing

ВКЛАД АЛЬБЕРА ФЕРА И ПЕТЕРА ГРЮНБЕРГА

Альбер Фер с коллегами исследовал систему из нескольких десятков чередующихся слоев железа и хрома. Чтобы получить должный эффект, ученые проводили эксперименты в условиях почти полного вакуума при низкой температуре. Группа Петера Грюнберга работала с более простой системой, состоящей из двух или трех слоев железа, проложенных слоем хрома.

Фер обнаружил, что электрическое сопротивление пленок уменьшается на 50%, когда относительная намагниченность ферромагнитных слоев изменяется от антипараллельной до параллельной конфигурации при наложении внешнего магнитного поля в условиях низких температур. У Грюнберга показатели меньше – всего 1, 5%, но при комнатной температуре (эта цифра выросла до 10% при температуре 5К). Физическая природа эффекта, который наблюдали независимо обе группы ученых, оказалась одинаковой. Ученые констатировали, что наблюдали совершенно новое явление. Альбер Фер был одним из тех, кто предложил теоретическое объяснение гигантского магнетосопротивления и в своей первой публикации 1988 года указал, что открытие может иметь большое значение для практики. Петер Грюнберг также отметил практический потенциал явления и одновременно с публикацией своих научных исследований в 1989 году предусмотрительно оформил патенты в Германии, Европе и США.

Но для широкого применения новой технологии требовалось разработать промышленный процесс получения тончайших слоев. Метод, который использовали и Грюнберг, и Фер, был достаточно сложным и дорогим. Он больше подходил для лабораторных исследований, а не для крупномасштабных промышленных разработок. Воплотить фундаментальные разработки в жизнь помогли работы англичанина Стюарта Паркина (Stuart Parkin). Он показал, что для изготовления тонкослойных магнитных “сэндвичей” можно использовать технологию магнетронного распыления, причем при комнатной температуре. И с 1997 года началось производство GMR-головок, которые позволили многократно увеличить емкость жестких дисков.

(Наука и жизнь №11, 2007г. )

Unit 8

Spontaneous Broken Symmetry in Subatomic Physics

The Nobel Prize in Physics 2008 — Press Release

October 7, 2008

The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics for 2008 with one half to Yoichiro Nambu Enrico Fermi Institute, University of Chicago, IL, USA, " for the discovery of the mechanism of spontaneous broken symmetry in subatomic physics" and the other half jointly to

Makoto Kobayashi, High Energy Accelerator Research Organization (KEK), Tsukuba, Japan and Toshihide Maskawa, Yukawa Institute for Theoretical Physics (YITP), Kyoto University, and Kyoto Sangyo University, Japan, " for the discovery of the origin of the broken symmetry which predicts the existence of at least three families of quarks in nature".

Passion for symmetry

The fact that our world does not behave perfectly symmetrically is due to deviations from symmetry at the microscopic level.

As early as 1960, Yoichiro Nambu formulated his mathematical description of spontaneous broken symmetry in elementary particle physics. Spontaneous broken symmetry conceals nature's order under an apparently jumbled surface. It has proved to be extremely useful, and Nambu's theories permeate the Standard Model of elementary particle physics. The Model unifies the smallest building blocks of all matter and three of nature's four forces in one single theory.

The spontaneous broken symmetries that Nambu studied, differ from the broken symmetries described by Makoto Kobayashi and Toshihide Maskawa. These spontaneous occurrences seem to have existed in nature since the very beginning of the universe and came as a complete surprise when they first appeared in particle experiments in 1964. It is only in recent years that scientists have come to fully confirm the explanations that Kobayashi and Maskawa made in 1972. It is for this work that they are now awarded the Nobel Prize in Physics. They explained broken symmetry within the framework of the Standard Model, but required that the Model be extended to three families of quarks. These predicted, hypothetical new quarks have recently appeared in physics experiments. As late as 2001, the two particle detectors BaBar at Stanford, USA and Belle at Tsukuba, Japan, both detected broken symmetries independently of each other. The results were exactly as Kobayashi and Maskawa had predicted almost three decades earlier.

A hitherto unexplained broken symmetry of the same kind lies behind the very origin of the cosmos in the Big Bang some 14 billion years ago. If equal amounts of matter and antimatter were created, they ought to have annihilated each other. But this did not happen, there was a tiny deviation of one extra particle of matter for every 10 billion antimatter particles. It is this broken symmetry that seems to have caused our cosmos to survive. The question of how this exactly happened still remains unanswered. Perhaps the new particle accelerator LHC at CERN in Geneva will unravel some of the mysteries that continue to puzzle us.

(http: //www. nobelprize. org/nobel_prizes/physics/laureates/2008/press. html)