Simeon A. Friedberg Professor Emeritus D.Sc., Carnegie Institute of Technology Email: saf@andrew.cmu.edu Phone: (412) 268-2735 FAX: (412) 681-0648

Professor Friedberg is engaged in research in low-temperature solid state physics with particular emphasis on magnetic ordering and collective behavior caused by interactions among transition metal or rare earth ions in various compounds. These include insulators and some high-Tc superconducting oxides. Among the problems under study are 1) long-range magnetic order in quasi-one-dimensional systems, 2) magnetic order in singlet ground state systems, 3) combined electron-nucleus ordering in induced-moment magnets with large hyperfine interaction, 4) ordering in magnets with dipolar and cooperative Jahn-Teller interactions 5) antiferromagnetic ordering of lanthanide (L) ions in high-Tc superconductors LBa₂ Cu₃ O_7-v. The experimental techniques used in this work include the measurement of magnetic susceptibility, magnetization, specific heat, magnetic resonance absorption and neutron diffraction. Most of these experiments are done at low temperatures and many involve the use of a ³He-³He dilution refrigerator.

Selected Publications

Lukin, J.A., S. Simizu, N.S. VanderVen and S.A. Friedberg, "Low-Dimensional Magnetic Behavior of alpha-CoC₂O₄ · 2H₂O," J. Magn. and Magn. Mat. 149(144): 1669 (1995).

Lukin, J.A., S.A. Friedberg, S. Chardarlapaty, W.W. Brubaker, C.C. Cinquina and G.C. DeFotis, "Heat Capacity and Magnetic Properties of CoCl₂ · H₂O," J. Appl. Phys. 75: 5529 (1994).

Petasis, D.T., N.S. VanderVen, S. Simizu and S.A. Friedberg, "Pair Interactions in Pr:La(CF₃SO₃)₃ · 9H₂O," J. Appl. Phys. 73(10): 6078 (1993).

Petasis, D.T., G.H. Bellesis, N.S. VanderVen and S.A. Friedberg, "Electron Paramagnetic Resonance of Ce³⁺ in La(CF₃SO₃)₃ · 9H₂O," J. Appl. Phys. 70: 5998 (1991).

Lukin, J.A., S.A. Friedberg and G.C. DeFotis, "Quasi-one-dimensional Antiferromagnetism in MnCI₂H₂O," J. Appl. Phys. 69: 5807 (1991).

Bellesis, G.H., S. Simizu and S.A. Friedberg, "Magnetic Ordering in Ho(CF₃SO₃)₃ · 9H₂O and Ho(C₂H₅SO₄)₃ · 9H₂O," J. Appl. Phys. 67: 5850 (1990).