During World War II, he joined the Submarine Operations Research Group (SORG). (He is mentioned on page 478 of RV Jones' book Most Secret War, published 1978.) He served in the United States Navy as a naval attache.
Kittel joined MIT again in 1945, this time as a research associate, remaining there until 1947. From 1947 to 1951, he worked for Bell Laboratories, New Jersey, USA, especially on ferromagnetism.[5]
Among other achievements, Kittel is credited with the theoretical discovery of the RKKY interaction (the first K standing for Kittel) and the Kittel magnon mode in ferromagnets.[7]
Kittel married Muriel A. Lister, at the time an English literature student, in 1938 during his time at Cambridge. The two had three kids: Peter, Ruth and Timothy. Lister, who went on to have a career as a scholarly translator, died in 2009 at the age of 93.[2]
Kittel died on May 15, 2019, at his home in Berkeley. He was 102.[8][9]
1958: Elementary Statistical Physics. New York: John Wiley & Sons. OCLC912372820. Reprinted five times by 1967; a reproduction was published in 2004 by Dover ISBN9780486435145