Stability Of Vertical Bloch Line Chains In Hard Magnetic Domains Of Garnet Bubble Films

Konish proposed the ultra-high-density Bloch line memory (BLM) scheme based on the magnetic bubble storage technology in 1983. Negative vertical Bloch line (VBL) pairs in the walls of stripe domains aligned in parallel are used as information carriers in BLM in which the presence and absence of VBL is represented by "1" and "0", respectively. Compared with magnetic bubble storage memory, the bit density of BLM increases drastically.The formation and stability of VBLs in the hard domains is very important to design and use ofBLM.Firstly, in two sorts of samples of different nominal composition, the relationship between the formation of the hard domains with the amplitude of bias field and pulse field, the width of pulse field, are investigated by series of pulse low-bias field.Secondly, the investigations of stability of VBLs in the hard domains in this paper are as follows: (1) The temperature stability of vertical Bloch lines in the domain walls of three kinds of hard domains in uncompressed states in same sample is investigated experimentally. There exists a critical temperature rangefor the break down of VBLs of the three hard kinds of domains in uncompressed state, i.e. [T01, T0 ], in whichT01 is the initial critical temperature of VBLs annihilation in the walls of three kinds of hard domains. It is found that the temperature at which VBLs start to break down is the same in the three kinds of hard domains. (T0)OHB, (T0)ID and (T0)IID are the lowest temperatures at which all VBLs in the walls of OHB, ID andIID are annihilated completely, and (T0)OHB <(T0)ID <(T0)t/D is obtained. (2) The temperature andin-plane field stability of vertical Bloch lines in the walls of three kinds of the hard domains in the uncompressed state in same sample is investigated experimentally. It is found there exists a critical in-plane field range at various temperatures in which vertical Bloch lines are unstable for the three hard kinds ofdomains, i.e., [ Hip(1) (T), Hip(2) (T) ]. Here, Hip(1) (T) are the initial critical in-plane fields at which VBLs in the walls of the three hard kinds of domains start to annihilate; while Hip(2) (T) are the lowest in-planefields at which all VBLs in the walls of OHBs, IDs and IIDs have annihilated completely. Hip(1)(T) is increase successively, Hip(2) (T) is the same in the three kinds of hard domains. Also, the critical in-planefield range [ H ip (T) , H'ip(2) (T) ] all decrease with the temperature increasing. And Hip(1) (T) andH ip (T) reach zero at T0 and To, respectively. (3) The stability of vertical Bloch lines in the first kind of dumbbell domains subjected to in-plane field at different static bias field is studied experimentally. It isfound there exists a critical static bias field (Hb)lh, when Hb<(Hb)lh, the critical in-plane fieldHip(1) and Hip(2)keep unchanged, respectively; whenHb >{Hb)th, the critical in-plane field Hip(1) and Hip(2) all decrease with the static bias field increasing. (4) Stripe-to-bubble transition (SBT) of the first kind of dumbbell domains, which are subjected to an in-plane field in a fixed static bias field Hb, is studied experimentally. The results suggest that there are three characteristic static bias fields from low to high, (Hb)h, {Hb), and (Hb)AI . When Hb<{Hb)h, the bubble domainstransformed from IDs after SBT take place are all soft bubbles (SB). When Hbis higher (Hb)/and (Hb)AI, the OHBs and IDs begin to appear in the domains from IDs, after SBT take place. The percentage of IDs in the domains from IDs, after SBT take place, increases to 100%. The minimal and maximum in-plane fields of SBT of IDs decrease as Hb increase. WhenHb {Hb)h,...