You can use tiledlayout with the spacing between the tiles set to zero.
Note that you will have to edit x-axes and y-axes properties (limits, ticks and tick-labels) accordingly.
x1 = [2.6795 3.46422 3.88829 4.00262 4.3035 4.54301];
y1 = [5.48 8.12e-4 1.2 27.9 6.59 5.17];
x2 = [2.054 2.08 2.091 2.099 2.103 2.112];
y2 = [0.125 0.14 0.118 0.099 0.257 0.082];
tiledlayout(2,1,'TileSpacing','none');
nexttile
plot(x1,y1)
%modify axis properties accordingly
xlim([2 4])
xticks(2:0.5:4)
%removing xtick labels as the labels will appear on the next tile
xticklabels([])
nexttile
plot(x2,y2)
%modifying axis properties to align with the previous tile
xlim([2 4])
xticks(2:0.5:4)
