Behavior Of The Hard Domains In Garnet Bubble Films

The researches of magnetic domain and magnetic domain wall theory are the important part in the magnetic field at all times.Furthermore the study of the behavior of the hard domains in garnet bubble films has important significance to the manufacture of Bloch line memory and the development of magnetic domain wall theory.In-plane field and temperature are the main factors which affect the vertical Bloch line (VBL) in hard domain wall.This paper studied the relationship of the behavior of hard domains with hardening pulse bias field,in-plane field and temperature.And the results obtained by our experiments are as follows:1.It's considered that the connection of the dynamic characteristics of dumbbell domain in liquid phase epitaxy garnet bubble films with the hardening pulse bias field.We find that the rotation direction of dumbbell domain produced by series of pulse bias fields method is related to the width of hardening pulse(Ï„_p)_h.When(Ï„_p)_h is small,all the dumbbell domains rotate anticlockwise.As(Ï„_p)_h is getting larger and larger,some dumbbell domains begin to rotate clockwise,that is so-called mixed region,finally all dumbbell domain will rotate clockwise.But the range of pulse(H_p)_h and the number of pulse(n_p)_h don't affect the rotating direction.However,the rotaing direction of the dumbbell domain produced by the method of low direct current bias field is related to the direct current bias fields H_b.When H_b is zero,the dumbbell domain shrinked from multi-branched domains all rotate anticlockwise;when H_b rises,there will appear mixed region;as H_b rises further,all rotate clockwise.Their rotating direction is independent of the width of hardening pulse (Ï„_p)_h,the range of hardening pulse(H_p)_h and the number of hardening pulse(n_p)_h. Compared the rotating behaviors of these hard domains,we arrive at a conclusion:the formation of the negative VBL chains are corresponding to the negative edge of pulse bias field,and that of the positive VBL chains are related to the positive edge. 2.The dynamic characteristics of dumbbell domain affectd by in-plane field are examined also in our experiments.In-plane field has no influence on the initial state of dumbbell domain,which means hard domains still keep their rotating direction after VBLs disappear in part.This fact proves that in-plane field don't affect the sign of VBL and supports the view of VBL disappear in pairs.3.The experiments test the influence of in-plane field on the three kinds of hard domains in liquid phase epitaxy garnet bubble films(ordinary hard bubbles,the first kind of dumbbell domain and the second kind of dumbbell domain,abbreviated as OHB,â… D andâ…¡D respectively).We observe that these three kinds of hard domains have the same scope of critical in-plane field[H_ip¹,H_ip²].This paper explains why the conclusion of (H_ip¹)_â…¡D <(H_ip¹)_â… D <(H_ip¹)_OHB is inaccurate.4.We studied how the direct current bias fields rebuilt and temperature alternately affect the VBL chains in domain wall of the three kinds of hard domains.We find an interval of critical temperature[T₁,T₂],which can make VBL chains breakdown and is related to the parameter of magnetic bubble material.Here T\ is the lowest threshold temperature where the VBL chains in domain wall become unstable,and T₂ is the lowest threshold temperature where the VBL chains breakdown completely.For the three kinds of hard domains,T₁ is the same,which means T₁ is independent of the number of VBL,whereas T₂ is rising as the number of VBL becomes larger.This proves VBL in hard domains wall breakdown gradually affected by temperature.And this paper testified that the disappearance of VBL is irrelevant to the rigidity of hard domains and negates Haisma's conclusion that the harder domains are more easily to lose VBL.