Hysteresis loop (initial magnetization and down to remanence)

Hi, i have a set of data with i need to make from U = f(t), voltage in function of time, to polarization J in function of magnetic field, H. The problem is, with all the formulas i used, it doesn't look at all like what i need. I will attach the code and the rezult. Please, i need help with this. Thanks a lot!

clear all;

clc;

timp = xlsread('1_ALL','A124600:A350000');

Ch1 = xlsread('1_ALL','B124600:B350000');

Ch2 = xlsread('1_ALL','C124600:C350000');

Ch3 = xlsread('1_ALL','D124600:D350000');

Ss = (pi.*(67.*10^-3).^2)./4;

miu0 = 4.*pi.*10.^-7;

B = (1./Ss).*Ch1;

S2 = (pi.*(10.*10.^-3).^2)./4;

miu0Happ = (1./(10.*S2)).*Ch3;

J = B - miu0Happ;

Happ = -(J - B)./miu0;

Nd = 1./4;

Hd = -Nd.*(J./miu0);

Heff = Happ - Hd;

B1 = miu0Happ + (1 - Nd).*J;

plot(J, Heff, 'LineWidth',2); grid on; hold on;

xlabel('H [A/m]','FontSize',14)

ylabel('J [T]','FontSize',14)

%plot(-J, -Heff, 'LineWidth',2); grid on; hold on;

plottools

And the original signal i have to transform is: