1. Full name: Nguyen Thi Minh Hong                                           2. Sex: Female               

3. Date of birth: 31/10/1981                                                        4. Place of birth: Ha Noi

5. Admission decision number: 3613/QĐ-SĐH dated 22/10/2009

6. Changes in academic process:

7. Official thesis title: Fabrication and study on some characteristic properties of nanostructured composites based on ferroelectric material.

8. Major: Nano Materials and Devices                                         9. Code: Pilot speciality

10. Supervisors: Assoc. Prof. Dr. Pham Duc Thang    

                           Prof. Dr. Nguyen Huu Duc

11. Summary of the new findings of the thesis:

Fabrication of nanostructured composites PZT/CoCr and PZT/NiFe/CoFe by sputtering on longitudinal and tranverse polarized piezoelectric PZT substrates.

The composites showed soft magnetic properties and in-plane  magnetic  anisotropy. Under applied electric voltage, magnetization M and its change DM depend on external electric field intensity and direction. At a = 0o, sample N2 has DMmax = 530 memu and sample D1 has DMmax = 1540 memu.

The electric voltage induced switching of magnetization has been observed at suitable voltage Uđ which depends on magnetic filed direction and intensity. At a = 0o, Hbias = - 50 Oe, Uđmin = 1 V for sample N4 and Uđmin = 18 V for sample D1. And at Hbias = 0, Uđmin = -70 V for sample N2 and Uđmin  = 21 V for sample D1.

Theoretical works indicated a transition thickness of magnetic layer dtr = 0.2 nm. The decrease in DHeffOP(U) is simliar to the change in M(U), reflected the strain-mediated magnetoelectric coupling as well as electric-voltage-controlled magnetic anisotropy in PZT/NiFe/CoFe with longitudinal polarized substrate PZT.

12. Practical applicability, if any:

13. Further research directions, if any:

14. Thesis-related publications:

[1] N.T.M. Hong, P.D. Thang, N.H. Tiep, L.V. Cuong and N.H. Duc, 2011, Voltage-controllable magnetic behavior in PZT/NiFe/CoFe nanocomposites, Adv. Nat. Sci: Nanosci. Nanotechnol. 2, 015015.

[2] N.T.M. Hong, P.D. Thang, N.H Duc, 2011, Converse magnetoelectric effect in PZT/NiFe/CoFe nanocomposites, Proceeding of The 3rd International Workshop on Nanotechnology and Application - IWNA, p.869. 

[3] N.T.M. Hong, P.T.Ha, B.N.Q. Trinh, P.H. Cong, N.D. Duc, D.D. Long, P.D. Thang, 2013, Size dependent electric field control of strain mediated magnetoelectric random access memory, Proceeding of The 4rd International Workshop on Nanotechnology and Application - IWNA, p.359.

[4] N.T.M. Hong, N.H. Duc and P.D. Thang, 2013, Converse magnetoelectric effect in PZT/NiFe/CoFe nanocomposites, Int. J. of Nanotechnology 10, 206.

[5] N.T. M. Hong, N.B. Doan, N.H. Tiep, L.V. Cuong, B.N.Q. Trinh, P.D. Thang and D.-H. Kim, 2013, Switchable Voltage Control of the Magnetic Anisotropy in Heterostructured Nanocomposites of CoFe/NiFe/PZT, Journal of the Korean Physical Society 63, August 2013, 812.

[6] N.T.M. Hong, P.T. Ha, L.V. Cuong, P.T. Long, P.D. Thang, 2014, Electrical field induced magnetization switching in CoFe/NiFe/PZT multiferroics, IEEE Transactions on Magnetics 50, 2005204.

[7] N.T.M. Hong, P.D. Thang, D.D. Long, P.T. Ha, N.N. Trung, P.H. Cong, N.D. Duc, 2014, The temperature-sensitivity of a critical electric field induced magnetic easy-axis reorientation ferromagnetic/ferroelectric layered heterostructures, Communications in Physics 24, 71.

[8] N.T.M. Hong, P.T. Ha, P.D. Thang, 2014, Structure and magnetic properties of PZT/CoCr heterostructures, Communications in Physics 24, 99.