Universidade de S˜ao Paulo Instituto de F´ısica Controle ótico e detecç˜ao de coerência de spin ...

208 Pages·2017·10.68 MB·English

Universidade de S˜ao Paulo
Instituto de F´ısica
Controle ´otico e detec¸c˜ao de coerˆencia de spin em sistemas
de multicamadas
Saeed Ullah
Orientador: Prof. Dr. Felix G. G. Hernandez
Tese de doutorado apresentado ao Instituto de
F´ısica da Universidade de S˜ao Paulo para a
obten¸c˜ao do t´ıtulo de Doutor em Ciˆencias
Banca Examinadora:
Prof. Dr. Felix G. G. Hernandez (IF-USP)
Prof. Dr. Valmir Antonio Chitta (IF-USP)
Prof. Dr. Luis Greg´orio Godoy de Vasconcelos Dias da Silva (IF-USP)
Prof. Dr. Marcio Peron Franco de Godoy (UFSCar)
Prof. Dr. Yara Galv˜ao Gobato (UFSCar)
Sa˜o Paulo - SP
2017
FICHA CATALOGRÁFICA
Preparada pelo Serviço de Biblioteca e Informação
do Instituto de Física da Universidade de São Paulo

Ullah, Saeed

Controle ótico e detecção de spin em sistemas de multicamadas.
São Paulo, 2017.

Tese (Doutorado) – Universidade de São Paulo. Instituto de Física.
Depto. de Física dos Materiais e Mecânica

Orientador: Prof. Dr. Félix Guillermo González Hernandez
Área de Concentração: Spintrônica de semicondutores

Unitermos: 1. Spintrônica; 2. Spin de elétron; 3. Arseneto de gálio;
4. Poços quânticos; 5. Tempo de relaxação de spin.

USP/IF/SBI-031/2017
Universidade de S˜ao Paulo
Instituto de F´ısica
Optical control and detection of spin coherence in
multilayer systems
Saeed Ullah
Advisor: Prof. Dr. Felix G. G. Hernandez
PhD Thesis submitted to the Institute
of Physics University of S˜ao Paulo to
obtain the title of Doctor of Science
Banca Examinadora:
Prof. Dr. Felix G. G. Hernandez (IF-USP)
Prof. Dr. Valmir Antonio Chitta (IF-USP)
Prof. Dr. Luis Greg´orio Godoy de Vasconcelos Dias da Silva (IF-USP)
Prof. Dr. Marcio Peron Franco de Godoy (UFSCar)
Prof. Dr. Yara Galv˜ao Gobato (UFSCar)
Sa˜o Paulo - SP
2017

Acknowledgements
ItwasMarch2013, whenItraveledS˜aoPaulo,Brazil. IstartedmyPh.D.withthestudy
on optical control and detection of spin coherence in multilayer systems, an exciting and
challengingtopicwhichwasverydifferentfrommybackground. Now,thisjourneycomes
to the end with this thesis.
First of all, special thanks to Almighty God for giving me the strength to surmount this
difficult task. Approaching the end of my Ph.D., I must declare what I have learned
during this time went way beyond the science aspect: Meeting the people from all over
the world taught me far more than I expected. It is with considerable sadness that I
prepare to leave the people I met in the last four years here in S˜ao Paulo with whom I
enjoyed spending my time, without whom it would not have been a pleasure nor fun. It
is my great pleasure to thank all those who, in one way or another, contributed to my
learning backgrounds, joyful moments, and fitness by accompanying me in sports.
Foremost, I could not have been more fortunate than to have Prof. Dr. Felix G G
Hernandez as my advisor. It has been a great pleasure working with him, and without
his guidance, encouragement, valuable suggestions, and patient supervision this thesis
would have never seen the light of day. The many conferences which Felix allowed me
to attend were a wonderful experience.
Secondly, my gratitude extends to the people (Prof. A. K. Bakarov and Prof. G. M.
Gusev) who grew and provided us the high-quality structures studied in this thesis.
I am grateful to the members of my qualification exam: Prof. Dr. Valmir Antonio
Chitta, Prof. Dr. Danilo Mustafa, and Prof. Dr. Armando Paduan Filho for their
valuable remarks and suggestion that encouraged me advancing this thesis.
I owe thanks to the former students who have enriched my time here, especially Abdur
Rahim for his true friendship; I cannot imagine S˜ao Paulo without him. Thinking about
ouradventuresinS˜aoCarlosandBahiaalwaysmakesmesentimentalfortheearlyyears.
i
Tomylabfellows: AminaSolanoLopesRibeiroandFlavioCompopianoDiasdeMoraes.
Thanks for helping to relax with a hot coffee and lots of laughs after lunch, and for all
great parties, dinners, and uncountable lively discussions we had together. Many thanks
for being so encouraging, positive and supportive. Thank you, Amina for giving ride to
my house and Flavio for the abstract translation.
I cordially acknowledge my homework team, without whom my first two years would
not have been as enjoyable or successful: Antonio Delgado de Pasquale, Danilo Pedrelli,
Fernando Takeshi Tanouye, Juan Enrique Cervantes and Tu´lio Brito Brasil. A big
thanks to Carlos Mario Diaz Solano, Diron, Harold Alberto Rojas Paez and Maximilia
Souza. We may have Kurt Gottfried, and Jackson problems to thank in part for our
initial bonds of friendship, but those bonds persisted as we all went off into our own
research worlds. Your friendship has been invaluable to me.
I had the pleasure to share the office (Sala 113) with Alexandre Raul, Carol Guandalin,
Diana Lizeth Torres Sanchez, Edgar Fernando Aliaga Ayllon, Gerson Pessoto, Jorge
Leon, Juan Pablo Badilla, Julio Cesar, Lilian Afonso Cˆandido, Natalia Bullaminut,
Thiago Melo, Vinicius, Victor Manotas and Zahra Sadre Momtaz. They were tirelessly
helping me in translations from Portuguese into English or any other thing.
To Ahmad Al Zeidan whose friendship made me feel stronger. Thanks for your time in
Natal especially in mergulho and for your special invitation to eat pizza with you (Uma
del´ıcia).
My special thanks also go to the peoples in CPG (Andrea, Claudia, Eber, and Paula.)
and the Secretaries of DFMT (Cecilia, Rosana, Sandra, and Tatiana.) for their supports
in all official documents and correspondences. I am also thankful to the people in
cryogenics and lab technicians Eron, Olimpio, Paulinho, and Renato for their help in
lab related stuff.
To my housemates: Anees Ahmad and Anwar Shamim for giving a nice company espe-
cially in our adventures in cooking and playing LUDO. Special thanks to Ajmir Khan
and Ali Paracha. It was always great to have you as neighbors and to sometimes spend
a break with you especially for a cup of tea after dinner. Also thanks for joining us in
Ramadan.
During my time in Brazil, I also enjoyed participating in sports, so I would like to
thank all people who shared the same interests with me and motivated me to work out.
Thanks, Asif Iqbal for providing the environment to play Cricket in USP.
I wish good luck to newcomers: Nicolas Massarico Kawahala and Suelen de Castro for
keepingtheshipafloat. SpecialthankstoSuelen,yoursupportinproofreadingmythesis
was simply great.
To Angela da Paz for giving a great service in bandija˜o since the first day, I started to
eat in bandij˜ao. Thanks for treating me like your son.
I extend my heartfelt thanks to all my Pakistani friends in S˜ao Paulo: Abdur Rahim,
AjmirKhan, AliParacha, AmirRana, AmnaNisar, AneesAhmad, AnwarShamim, Asif
Iqbal, Bakhat Ali, Faiz Ahmad, Hanif Ur Rehman, Haq Nawaz, Huma Asif, Irfan Khan,
Ishtiaq Ahmed, Latif Ullah, M Nawaz, M Khalid, Niaz Marwat, Shafqat Batool, Taj Ali
Khan and Zia Khan for their moral support. I want also to say thanks to all my dear
friends in Pakistan and also to those scattered around the globe for the great time we
have whenever we meet. But there are much more and I am equally grateful to all of
them. I thank each and everyone involved for their contribution. I guess I owe you all
a hug.
MyexperienceintheBrazilwascompletedwithagreatcircleoffriendswhoIspenttime
after work. People who I could truly connect with, for whom the difference in culture
didnotbecomeabarrierforustobecomegoodfriends. Iwouldliketothankyouall, for
beingsuchgoodfriends, teachingmesomanythings, andsharingyourcultureswithme:
Adriana Carvalho de Araujo, Camila, Danial, Habib Hadad, Jos´e Antonio Domingues,
Julia and her daughter Myrella, Tania Medina Torrejon, Vera and Zenilda. I can truly
say that meeting you was one of my greatest fortunes in the last couple of years. I
believe we will always stay good friends, regardless of the distance.
I great fully acknowledge the financial support from the TWAS (The academy of sci-
ence for developing worlds) and CNPq (The Brazilian national council for scientific and
technological developments).
Besides their major role in my existence, all this would not have been possible without
the loving support I received from my family. They tried their best to get me a better
education. In this world, there is nothing more valuable than your family. I couldn’t
have asked for a better family and I don’t know how to put in words how much I love
them. I hope they know.